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Python Basics Course Roadmap

Introduction to Python

Learn Python from scratch with this complete beginner roadmap. Master Python syntax, variables, loops, functions, OOP, file handling, modules, projects, and bes

Module 1: Introduction to Python

Welcome to Module 1 of the Python Programming Course.

Python is one of the most popular programming languages in the world. It is beginner-friendly, readable, and powerful enough to build web applications, automation scripts, artificial intelligence systems, data science applications, APIs, and much more.

In this module, you will learn the fundamentals of Python and write your first Python programs.

By the end of this lesson, you will understand:

What Python is
The history of Python
Why Python is popular
Important Python features
Real-world Python applications
How to install Python
How to install VS Code
How to run Python programs
Python interactive mode and script mode
The print() function
Python comments
Keywords and identifiers
Variables and naming conventions

What Is Python?

Python is a high-level, general-purpose programming language known for its simple and readable syntax.

Python supports several programming paradigms, including:

Procedural programming
Object-oriented programming
Functional programming

One of Python's biggest advantages is that beginners can write useful programs with relatively little code.

For example:

python
1print("Hello, Python!")

Output:

text
1Hello, Python!

The print() function sends text or other values to the program's standard output.

Python is also dynamically typed, which means you generally do not need to declare a variable's type explicitly.

python
1name = "Alice"
2age = 22

Python determines the appropriate types from the assigned values.

History of Python

Python was created by Guido van Rossum and was first released publicly in 1991.

The language was designed with a strong emphasis on:

Readability
Simplicity
Developer productivity
Clear syntax

Python later evolved through several major versions.

The most important distinction for modern developers is between Python 2 and Python 3. Python 2 reached its official end of life in 2020, so new projects should use Python 3.

Today, Python is widely used in software development, automation, data science, artificial intelligence, education, and research.

Why Learn Python?

Python is an excellent programming language for beginners because its syntax is relatively easy to read and understand.

Consider this example:

python
1for number in range(1, 6):
2    print(number)

Output:

text
11
22
33
44
55

The code is short while still being easy to understand.

Some major reasons to learn Python include:

Easy-to-Read Syntax

Python code often looks close to plain English.

python
1name = "Alice"
2
3if name == "Alice":
4    print("Welcome, Alice!")

Large Ecosystem

Python has thousands of libraries and frameworks for different areas of development.

For example:

Django and Flask for web development
NumPy and pandas for data analysis
PyTorch and TensorFlow for machine learning
Requests for HTTP requests
FastAPI for APIs
Selenium and Playwright for browser automation

Cross-Platform

Python programs can run on major operating systems such as:

Windows
Linux
macOS

Strong Community

Python has a large global developer community, which means beginners can find extensive documentation, tutorials, libraries, and troubleshooting resources.

Features of Python

Python provides several features that make it useful for both beginners and professional developers.

Simple and Readable Syntax

Python uses indentation to define code blocks.

python
1age = 20
2
3if age >= 18:
4    print("Adult")

The indentation is part of Python's syntax and is important for correctly structuring programs.

Dynamically Typed

You do not normally specify the variable type when assigning a value.

python
1name = "Alice"
2age = 25
3price = 99.99

Python associates each value with its type automatically.

Object-Oriented

Python supports object-oriented programming using classes and objects.

python
1class Student:
2    def __init__(self, name):
3        self.name = name
4
5student = Student("Alice")
6
7print(student.name)

Output:

text
1Alice

Automatic Memory Management

Python automatically manages memory and provides garbage collection to help reclaim memory that is no longer being used.

Large Standard Library

Python includes a large collection of built-in modules for tasks such as:

Working with files
Dates and times
Mathematics
JSON
Operating system operations
Regular expressions
Networking

Portable

Python programs can generally be moved between operating systems with little or no modification, although platform-specific dependencies can sometimes require changes.

Real-World Applications of Python

Python is used across many areas of technology.

Web Development

Frameworks such as Django, Flask, and FastAPI can be used to build websites and backend APIs.

Example:

python
1from fastapi import FastAPI
2
3app = FastAPI()
4
5@app.get("/")
6def home():
7    return {"message": "Hello, Python!"}

Artificial Intelligence and Machine Learning

Python is one of the most widely used languages for AI and machine learning.

Popular libraries include:

PyTorch
TensorFlow
scikit-learn
NumPy
pandas

Data Science

Python is frequently used for:

Data cleaning
Data analysis
Data visualization
Statistical computing
Machine learning

Automation

Python can automate repetitive tasks.

python
1for task_number in range(1, 4):
2    print(f"Task {task_number} completed")

Output:

text
1Task 1 completed
2Task 2 completed
3Task 3 completed

Cybersecurity

Python can be used to create security tools, automate security tasks, analyze logs, process network data, and build defensive security utilities.

Web Scraping

Python libraries can be used to retrieve and process information from websites where scraping is permitted.

APIs and Backend Development

Python can be used to build REST APIs and backend services.

Robotics and IoT

Python is also used in robotics, Raspberry Pi projects, hardware automation, and Internet of Things applications.

Installing Python

Before writing Python programs, you need to install Python 3.

Download Python from the official Python website.

Download Python from python.org

After installation, open a terminal or command prompt and verify the installation.

Windows

bash
1python --version

If your system uses the Python launcher, you can also try:

bash
1py --version

Linux and macOS

bash
1python3 --version

Example output:

text
1Python 3.13.2

Your exact version may be different because Python releases continue to change.

Add Python to PATH on Windows

During Windows installation, enable the option to add Python to your PATH when available.

This allows commands such as:

bash
1python

to be executed directly from the terminal.

Installing Visual Studio Code

Visual Studio Code (VS Code) is a lightweight source-code editor that works well for Python development.

Download Visual Studio Code

After installing VS Code:

Open VS Code.
Open the Extensions panel.
Search for the official Python extension.
Install the extension.
Open or create a Python file.

Useful extensions and tools include:

Python
Pylance
Black Formatter

For beginners, the Python and Pylance extensions are especially useful for code completion, error detection, debugging, and type information.

Installing PyCharm

PyCharm is a Python-focused integrated development environment (IDE) developed by JetBrains.

Download PyCharm

PyCharm provides features such as:

Intelligent code completion
Debugging
Refactoring
Git integration
Integrated terminal
Project management
Python environment management

You do not need both VS Code and PyCharm. Beginners can choose either editor based on their preference.

Running Python Programs

There are several ways to run Python code.

Common options include:

Python interactive interpreter
Terminal or command prompt
VS Code
PyCharm
Jupyter Notebook

For beginners, starting with the terminal and a .py file is a good way to understand how Python programs work.

Python Interactive Interpreter

The Python interpreter provides an interactive environment where you can enter Python expressions and immediately see their results.

Open a terminal and run:

bash
1python

On systems where Python 3 uses the python3 command:

bash
1python3

You may see something similar to:

text
1Python 3.13.2
2>>>

The >>> prompt means Python is ready to execute your command.

Try:

python
1>>> 5 + 8
213

Another example:

python
1>>> name = "Alice"
2>>> print(name)
3Alice

The interactive interpreter is useful for:

Learning Python
Testing small expressions
Checking syntax
Experimenting with functions
Debugging simple problems

To exit:

python
1>>> exit()

You can also use Ctrl+D on Linux/macOS or Ctrl+Z followed by Enter on Windows.

Interactive Mode vs Script Mode

Python can commonly be used in two basic ways: interactive mode and script mode.

Interactive Mode

You enter Python instructions directly into the interpreter.

python
1>>> 10 + 20
230
3
4>>> 7 * 8
556

This is useful when you want to test something quickly.

Script Mode

In script mode, you save Python code in a file with the .py extension.

Create a file named:

text
1hello.py

Add:

python
1print("Welcome to Python")

Then run it from the terminal.

Windows:

bash
1python hello.py

Linux/macOS:

bash
1python3 hello.py

Output:

text
1Welcome to Python

For larger programs, script mode is much more practical because your code can be saved, edited, tested, and reused.

Your First Python Program

Let's write a simple Python program.

Create a file named:

text
1hello.py

Add this code:

python
1print("Hello, World!")

Run the program:

bash
1python hello.py

Output:

text
1Hello, World!

Congratulations! You have written your first Python program.

Understanding the print() Function

The print() function displays values in the program's standard output.

Example:

python
1print("Hello World")
2print("Welcome to Python")
3print("Happy Coding!")

Output:

text
1Hello World
2Welcome to Python
3Happy Coding!

You can also print numbers:

python
1print(10)
2print(25 + 15)
3print(100 / 4)

Output:

text
110
240
325.0

You can print multiple values:

python
1name = "Alice"
2age = 22
3
4print("Name:", name)
5print("Age:", age)

Output:

text
1Name: Alice
2Age: 22

Using f-Strings

For formatted output, Python provides f-strings.

python
1name = "Alice"
2age = 22
3
4print(f"My name is {name} and I am {age} years old.")

Output:

text
1My name is Alice and I am 22 years old.

You will learn more about formatted strings later in the course.

Python Comments

Comments are notes written in source code to explain what the code does.

Python ignores comments during normal program execution.

A single-line comment begins with #.

python
1# Store the user's name
2name = "Alice"
3
4print(name)

Comments are useful for explaining complex logic and documenting important decisions.

Multi-Line Comments

Python does not have a dedicated multiline comment syntax like some other languages.

Triple-quoted strings can span multiple lines:

python
1"""
2This is a multi-line string.
3It is not technically a comment.
4"""

When used as a standalone expression, Python does not assign this string to a variable. Developers sometimes use this style as a comment, but docstrings are the intended way to document functions, classes, and modules.

Example:

python
1def greet(name):
2    """Return a greeting for the supplied name."""
3    return f"Hello, {name}!"

The string inside the function is a docstring, not simply a comment.

Python Keywords

Keywords are reserved words that have special meanings in Python.

Some Python keywords include:

text
1if
2else
3elif
4for
5while
6class
7def
8return
9import
10from
11try
12except
13with
14True
15False
16None

You cannot use a Python keyword as a variable name.

Incorrect:

python
1class = 10

This produces a syntax error because class is a reserved keyword.

Correct:

python
1class_name = "Python"

You can see Python's keyword list programmatically:

python
1import keyword
2
3print(keyword.kwlist)

This is useful when working with different Python versions because the keyword list can change over time.

Python Identifiers

An identifier is a name used to identify a programming element such as a variable, function, class, or module.

Examples:

python
1student_name = "Alice"
2total_marks = 450
3
4def calculate_total():
5    pass
6
7class Student:
8    pass

Here:

student_name is a variable identifier.
total_marks is a variable identifier.
calculate_total is a function identifier.
Student is a class identifier.

Rules for Python Identifiers

A Python identifier:

Can contain letters.
Can contain numbers after the first character.
Can contain underscores.
Cannot begin with a number.
Cannot contain spaces.
Cannot contain characters such as - or @.
Cannot be a reserved keyword.
Is case-sensitive.

Valid examples:

python
1student
2student_name
3age1
4total_marks
5_user_name

Invalid examples:

python
11student
2student-name
3student name
4class

Python Variables

A variable is a name that refers to a value.

Example:

python
1name = "John"
2age = 21
3height = 5.8
4is_student = True
5
6print(name)
7print(age)
8print(height)
9print(is_student)

Output:

text
1John
221
35.8
4True

Python does not require you to declare the type before assigning a value.

For example:

python
1name = "Alice"

Python creates a string value and binds the name name to that value.

You can inspect the type using type():

python
1name = "Alice"
2age = 22
3
4print(type(name))
5print(type(age))

Output:

text
1<class 'str'>
2<class 'int'>

The exact representation may vary slightly between Python environments, but str and int indicate the respective data types.

Assigning Multiple Variables

Python allows multiple assignments in a single statement.

python
1name, age, city = "Alice", 22, "Delhi"
2
3print(name)
4print(age)
5print(city)

Output:

text
1Alice
222
3Delhi

You can also assign the same value to multiple variables:

python
1x = y = z = 0
2
3print(x)
4print(y)
5print(z)

Output:

text
10
20
30

Python Variable Naming Convention

Meaningful variable names make programs easier to read and maintain.

Prefer:

python
1student_name = "Alice"
2total_marks = 450
3user_age = 22
4is_logged_in = True

Avoid unclear names when they do not communicate meaning:

python
1a = "Alice"
2b = 450
3c = 22

Python's common naming convention for variables and functions is snake_case.

Example:

python
1first_name = "Alice"
2last_name = "Smith"
3
4full_name = first_name + " " + last_name
5
6print(full_name)

Output:

text
1Alice Smith

For constants, Python commonly uses uppercase names:

python
1MAX_USERS = 100
2PI = 3.14159

These are conventions rather than enforced language rules.

Common Beginner Mistakes

When learning Python, beginners often encounter a few common problems.

Forgetting Indentation

Incorrect:

python
1age = 20
2
3if age >= 18:
4print("Adult")

Correct:

python
1age = 20
2
3if age >= 18:
4    print("Adult")

Using a Keyword as a Variable

Incorrect:

python
1for = 10

Correct:

python
1loop_count = 10

Starting a Variable Name With a Number

Incorrect:

python
11name = "Alice"

Correct:

python
1name1 = "Alice"

Using Hyphens in Identifiers

Incorrect:

python
1student-name = "Alice"

Correct:

python
1student_name = "Alice"

Practical Beginner Project

Let's combine several concepts from this module.

Create a file named:

text
1student_profile.py

Add:

python
1# Student profile program
2
3name = "Alice"
4age = 21
5city = "Delhi"
6course = "Python Programming"
7
8print("Student Profile")
9print("----------------")
10print(f"Name: {name}")
11print(f"Age: {age}")
12print(f"City: {city}")
13print(f"Course: {course}")

Output:

text
1Student Profile
2----------------
3Name: Alice
4Age: 21
5City: Delhi
6Course: Python Programming

This small program demonstrates:

Comments
Variables
Strings
Integers
print()
f-strings
Meaningful variable names

Module Summary

In this module, you learned the fundamentals required to begin programming with Python.

You learned:

What Python is
Python's history
Why Python is popular
Important Python features
Real-world Python applications
How to install Python
How to verify a Python installation
How to install VS Code
How to install PyCharm
How to run Python programs
Python's interactive interpreter
Interactive mode
Script mode
The .py file extension
The print() function
Comments and docstrings
Python keywords
Identifiers
Variables
Variable naming conventions
Common beginner mistakes

These concepts provide the foundation for the rest of the course.

Practice Exercises

Try these exercises without looking at the solution first.

Exercise 1: Check Python

Install Python and verify your Python 3 version from the terminal.

Exercise 2: Hello Python

Create a file named hello.py and print:

text
1Hello, Python!
2I am learning programming.

Exercise 3: Student Information

Create variables for:

Name
Age
City
Course

Then display them using print().

Exercise 4: Personal Introduction

Create a program that prints a sentence containing your name, age, and favorite programming language.

Exercise 5: Comments

Write a Python program containing at least three useful comments.

Exercise 6: Variables

Create five variables using meaningful names and display their values.

Exercise 7: Identifier Practice

Identify which of the following are valid Python identifiers:

text
1student_name
22students
3total_marks
4student-name
5_user
6class
7age2

Exercise 8: Interactive Mode

Open the Python interpreter and calculate:

python
125 + 75
212 * 8
3100 / 4
42 ** 5

Exercise 9: Automation Practice

Write a loop that prints:

text
1Task 1 completed
2Task 2 completed
3Task 3 completed
4Task 4 completed
5Task 5 completed

Exercise 10: Student Profile

Create your own student profile program using variables, comments, and f-strings.

Quiz

Question 1: Who created Python?

A. James Gosling B. Dennis Ritchie C. Guido van Rossum D. Bjarne Stroustrup

Answer: C. Guido van Rossum

Question 2: Which file extension is normally used for Python source files?

A. .java B. .py C. .cpp D. .js

Answer: B. .py

Question 3: Which function is commonly used to display output?

python
1print()

Question 4: Which symbol starts a single-line comment in Python?

A. // B. /* C. # D. --

Answer: C. #

Question 5: Which is a valid Python variable name?

A. 2name B. student-name C. student_name D. student name

Answer: C. student_name

Question 6: Is Python dynamically typed?

Answer: Yes. Python determines the type of a value at runtime, and variables do not normally require explicit type declarations.

What's Next?

In the next module, you will learn about Python Variables and Data Types in greater detail.

You will explore:

Python's built-in data types
Integers
Floating-point numbers
Strings
Booleans
Lists
Tuples
Sets
Dictionaries
type()
Type conversion
User input
Output formatting

These concepts will help you move from simple Python programs to interactive programs that can process and manipulate real data.

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Introduction to Python

Learn Python from scratch with this complete beginner roadmap. Master Python syntax, variables, loops, functions, OOP, file handling, modules, projects, and bes

Module 1: Introduction to Python

Welcome to Module 1 of the Python Programming Course.

In this module, you will learn the fundamentals of Python and write your first Python programs.

By the end of this lesson, you will understand:

What Python is
The history of Python
Why Python is popular
Important Python features
Real-world Python applications
How to install Python
How to install VS Code
How to run Python programs
Python interactive mode and script mode
The print() function
Python comments
Keywords and identifiers
Variables and naming conventions

What Is Python?

Python is a high-level, general-purpose programming language known for its simple and readable syntax.

Python supports several programming paradigms, including:

Procedural programming
Object-oriented programming
Functional programming

One of Python's biggest advantages is that beginners can write useful programs with relatively little code.

For example:

python
1print("Hello, Python!")

Output:

text
1Hello, Python!

The print() function sends text or other values to the program's standard output.

Python is also dynamically typed, which means you generally do not need to declare a variable's type explicitly.

python
1name = "Alice"
2age = 22

Python determines the appropriate types from the assigned values.

History of Python

Python was created by Guido van Rossum and was first released publicly in 1991.

The language was designed with a strong emphasis on:

Readability
Simplicity
Developer productivity
Clear syntax

Python later evolved through several major versions.

The most important distinction for modern developers is between Python 2 and Python 3. Python 2 reached its official end of life in 2020, so new projects should use Python 3.

Today, Python is widely used in software development, automation, data science, artificial intelligence, education, and research.

Why Learn Python?

Python is an excellent programming language for beginners because its syntax is relatively easy to read and understand.

Consider this example:

python
1for number in range(1, 6):
2    print(number)

Output:

text
11
22
33
44
55

The code is short while still being easy to understand.

Some major reasons to learn Python include:

Easy-to-Read Syntax

Python code often looks close to plain English.

python
1name = "Alice"
2
3if name == "Alice":
4    print("Welcome, Alice!")

Large Ecosystem

Python has thousands of libraries and frameworks for different areas of development.

For example:

Django and Flask for web development
NumPy and pandas for data analysis
PyTorch and TensorFlow for machine learning
Requests for HTTP requests
FastAPI for APIs
Selenium and Playwright for browser automation

Cross-Platform

Python programs can run on major operating systems such as:

Windows
Linux
macOS

Strong Community

Python has a large global developer community, which means beginners can find extensive documentation, tutorials, libraries, and troubleshooting resources.

Features of Python

Python provides several features that make it useful for both beginners and professional developers.

Simple and Readable Syntax

Python uses indentation to define code blocks.

python
1age = 20
2
3if age >= 18:
4    print("Adult")

The indentation is part of Python's syntax and is important for correctly structuring programs.

Dynamically Typed

You do not normally specify the variable type when assigning a value.

python
1name = "Alice"
2age = 25
3price = 99.99

Python associates each value with its type automatically.

Object-Oriented

Python supports object-oriented programming using classes and objects.

python
1class Student:
2    def __init__(self, name):
3        self.name = name
4
5student = Student("Alice")
6
7print(student.name)

Output:

text
1Alice

Automatic Memory Management

Python automatically manages memory and provides garbage collection to help reclaim memory that is no longer being used.

Large Standard Library

Python includes a large collection of built-in modules for tasks such as:

Working with files
Dates and times
Mathematics
JSON
Operating system operations
Regular expressions
Networking

Portable

Python programs can generally be moved between operating systems with little or no modification, although platform-specific dependencies can sometimes require changes.

Real-World Applications of Python

Python is used across many areas of technology.

Web Development

Frameworks such as Django, Flask, and FastAPI can be used to build websites and backend APIs.

Example:

python
1from fastapi import FastAPI
2
3app = FastAPI()
4
5@app.get("/")
6def home():
7    return {"message": "Hello, Python!"}

Artificial Intelligence and Machine Learning

Python is one of the most widely used languages for AI and machine learning.

Popular libraries include:

PyTorch
TensorFlow
scikit-learn
NumPy
pandas

Data Science

Python is frequently used for:

Data cleaning
Data analysis
Data visualization
Statistical computing
Machine learning

Automation

Python can automate repetitive tasks.

python
1for task_number in range(1, 4):
2    print(f"Task {task_number} completed")

Output:

text
1Task 1 completed
2Task 2 completed
3Task 3 completed

Cybersecurity

Python can be used to create security tools, automate security tasks, analyze logs, process network data, and build defensive security utilities.

Web Scraping

Python libraries can be used to retrieve and process information from websites where scraping is permitted.

APIs and Backend Development

Python can be used to build REST APIs and backend services.

Robotics and IoT

Python is also used in robotics, Raspberry Pi projects, hardware automation, and Internet of Things applications.

Installing Python

Before writing Python programs, you need to install Python 3.

Download Python from the official Python website.

Download Python from python.org

After installation, open a terminal or command prompt and verify the installation.

Windows

bash
1python --version

If your system uses the Python launcher, you can also try:

bash
1py --version

Linux and macOS

bash
1python3 --version

Example output:

text
1Python 3.13.2

Your exact version may be different because Python releases continue to change.

Add Python to PATH on Windows

During Windows installation, enable the option to add Python to your PATH when available.

This allows commands such as:

bash
1python

to be executed directly from the terminal.

Installing Visual Studio Code

Visual Studio Code (VS Code) is a lightweight source-code editor that works well for Python development.

Download Visual Studio Code

After installing VS Code:

Open VS Code.
Open the Extensions panel.
Search for the official Python extension.
Install the extension.
Open or create a Python file.

Useful extensions and tools include:

Python
Pylance
Black Formatter

For beginners, the Python and Pylance extensions are especially useful for code completion, error detection, debugging, and type information.

Installing PyCharm

PyCharm is a Python-focused integrated development environment (IDE) developed by JetBrains.

Download PyCharm

PyCharm provides features such as:

Intelligent code completion
Debugging
Refactoring
Git integration
Integrated terminal
Project management
Python environment management

You do not need both VS Code and PyCharm. Beginners can choose either editor based on their preference.

Running Python Programs

There are several ways to run Python code.

Common options include:

Python interactive interpreter
Terminal or command prompt
VS Code
PyCharm
Jupyter Notebook

For beginners, starting with the terminal and a .py file is a good way to understand how Python programs work.

Python Interactive Interpreter

The Python interpreter provides an interactive environment where you can enter Python expressions and immediately see their results.

Open a terminal and run:

bash
1python

On systems where Python 3 uses the python3 command:

bash
1python3

You may see something similar to:

text
1Python 3.13.2
2>>>

The >>> prompt means Python is ready to execute your command.

Try:

python
1>>> 5 + 8
213

Another example:

python
1>>> name = "Alice"
2>>> print(name)
3Alice

The interactive interpreter is useful for:

Learning Python
Testing small expressions
Checking syntax
Experimenting with functions
Debugging simple problems

To exit:

python
1>>> exit()

You can also use Ctrl+D on Linux/macOS or Ctrl+Z followed by Enter on Windows.

Interactive Mode vs Script Mode

Python can commonly be used in two basic ways: interactive mode and script mode.

Interactive Mode

You enter Python instructions directly into the interpreter.

python
1>>> 10 + 20
230
3
4>>> 7 * 8
556

This is useful when you want to test something quickly.

Script Mode

In script mode, you save Python code in a file with the .py extension.

Create a file named:

text
1hello.py

Add:

python
1print("Welcome to Python")

Then run it from the terminal.

Windows:

bash
1python hello.py

Linux/macOS:

bash
1python3 hello.py

Output:

text
1Welcome to Python

For larger programs, script mode is much more practical because your code can be saved, edited, tested, and reused.

Your First Python Program

Let's write a simple Python program.

Create a file named:

text
1hello.py

Add this code:

python
1print("Hello, World!")

Run the program:

bash
1python hello.py

Output:

text
1Hello, World!

Congratulations! You have written your first Python program.

Understanding the print() Function

The print() function displays values in the program's standard output.

Example:

python
1print("Hello World")
2print("Welcome to Python")
3print("Happy Coding!")

Output:

text
1Hello World
2Welcome to Python
3Happy Coding!

You can also print numbers:

python
1print(10)
2print(25 + 15)
3print(100 / 4)

Output:

text
110
240
325.0

You can print multiple values:

python
1name = "Alice"
2age = 22
3
4print("Name:", name)
5print("Age:", age)

Output:

text
1Name: Alice
2Age: 22

Using f-Strings

For formatted output, Python provides f-strings.

python
1name = "Alice"
2age = 22
3
4print(f"My name is {name} and I am {age} years old.")

Output:

text
1My name is Alice and I am 22 years old.

You will learn more about formatted strings later in the course.

Python Comments

Comments are notes written in source code to explain what the code does.

Python ignores comments during normal program execution.

A single-line comment begins with #.

python
1# Store the user's name
2name = "Alice"
3
4print(name)

Comments are useful for explaining complex logic and documenting important decisions.

Multi-Line Comments

Python does not have a dedicated multiline comment syntax like some other languages.

Triple-quoted strings can span multiple lines:

python
1"""
2This is a multi-line string.
3It is not technically a comment.
4"""

Example:

python
1def greet(name):
2    """Return a greeting for the supplied name."""
3    return f"Hello, {name}!"

The string inside the function is a docstring, not simply a comment.

Python Keywords

Keywords are reserved words that have special meanings in Python.

Some Python keywords include:

text
1if
2else
3elif
4for
5while
6class
7def
8return
9import
10from
11try
12except
13with
14True
15False
16None

You cannot use a Python keyword as a variable name.

Incorrect:

python
1class = 10

This produces a syntax error because class is a reserved keyword.

Correct:

python
1class_name = "Python"

You can see Python's keyword list programmatically:

python
1import keyword
2
3print(keyword.kwlist)

This is useful when working with different Python versions because the keyword list can change over time.

Python Identifiers

An identifier is a name used to identify a programming element such as a variable, function, class, or module.

Examples:

python
1student_name = "Alice"
2total_marks = 450
3
4def calculate_total():
5    pass
6
7class Student:
8    pass

Here:

student_name is a variable identifier.
total_marks is a variable identifier.
calculate_total is a function identifier.
Student is a class identifier.

Rules for Python Identifiers

A Python identifier:

Can contain letters.
Can contain numbers after the first character.
Can contain underscores.
Cannot begin with a number.
Cannot contain spaces.
Cannot contain characters such as - or @.
Cannot be a reserved keyword.
Is case-sensitive.

Valid examples:

python
1student
2student_name
3age1
4total_marks
5_user_name

Invalid examples:

python
11student
2student-name
3student name
4class

Python Variables

A variable is a name that refers to a value.

Example:

python
1name = "John"
2age = 21
3height = 5.8
4is_student = True
5
6print(name)
7print(age)
8print(height)
9print(is_student)

Output:

text
1John
221
35.8
4True

Python does not require you to declare the type before assigning a value.

For example:

python
1name = "Alice"

Python creates a string value and binds the name name to that value.

You can inspect the type using type():

python
1name = "Alice"
2age = 22
3
4print(type(name))
5print(type(age))

Output:

text
1<class 'str'>
2<class 'int'>

The exact representation may vary slightly between Python environments, but str and int indicate the respective data types.

Assigning Multiple Variables

Python allows multiple assignments in a single statement.

python
1name, age, city = "Alice", 22, "Delhi"
2
3print(name)
4print(age)
5print(city)

Output:

text
1Alice
222
3Delhi

You can also assign the same value to multiple variables:

python
1x = y = z = 0
2
3print(x)
4print(y)
5print(z)

Output:

text
10
20
30

Python Variable Naming Convention

Meaningful variable names make programs easier to read and maintain.

Prefer:

python
1student_name = "Alice"
2total_marks = 450
3user_age = 22
4is_logged_in = True

Avoid unclear names when they do not communicate meaning:

python
1a = "Alice"
2b = 450
3c = 22

Python's common naming convention for variables and functions is snake_case.

Example:

python
1first_name = "Alice"
2last_name = "Smith"
3
4full_name = first_name + " " + last_name
5
6print(full_name)

Output:

text
1Alice Smith

For constants, Python commonly uses uppercase names:

python
1MAX_USERS = 100
2PI = 3.14159

These are conventions rather than enforced language rules.

Common Beginner Mistakes

When learning Python, beginners often encounter a few common problems.

Forgetting Indentation

Incorrect:

python
1age = 20
2
3if age >= 18:
4print("Adult")

Correct:

python
1age = 20
2
3if age >= 18:
4    print("Adult")

Using a Keyword as a Variable

Incorrect:

python
1for = 10

Correct:

python
1loop_count = 10

Starting a Variable Name With a Number

Incorrect:

python
11name = "Alice"

Correct:

python
1name1 = "Alice"

Using Hyphens in Identifiers

Incorrect:

python
1student-name = "Alice"

Correct:

python
1student_name = "Alice"

Practical Beginner Project

Let's combine several concepts from this module.

Create a file named:

text
1student_profile.py

Add:

python
1# Student profile program
2
3name = "Alice"
4age = 21
5city = "Delhi"
6course = "Python Programming"
7
8print("Student Profile")
9print("----------------")
10print(f"Name: {name}")
11print(f"Age: {age}")
12print(f"City: {city}")
13print(f"Course: {course}")

Output:

text
1Student Profile
2----------------
3Name: Alice
4Age: 21
5City: Delhi
6Course: Python Programming

This small program demonstrates:

Comments
Variables
Strings
Integers
print()
f-strings
Meaningful variable names

Module Summary

In this module, you learned the fundamentals required to begin programming with Python.

You learned:

What Python is
Python's history
Why Python is popular
Important Python features
Real-world Python applications
How to install Python
How to verify a Python installation
How to install VS Code
How to install PyCharm
How to run Python programs
Python's interactive interpreter
Interactive mode
Script mode
The .py file extension
The print() function
Comments and docstrings
Python keywords
Identifiers
Variables
Variable naming conventions
Common beginner mistakes

These concepts provide the foundation for the rest of the course.

Practice Exercises

Try these exercises without looking at the solution first.

Exercise 1: Check Python

Install Python and verify your Python 3 version from the terminal.

Exercise 2: Hello Python

Create a file named hello.py and print:

text
1Hello, Python!
2I am learning programming.

Exercise 3: Student Information

Create variables for:

Name
Age
City
Course

Then display them using print().

Exercise 4: Personal Introduction

Create a program that prints a sentence containing your name, age, and favorite programming language.

Exercise 5: Comments

Write a Python program containing at least three useful comments.

Exercise 6: Variables

Create five variables using meaningful names and display their values.

Exercise 7: Identifier Practice

Identify which of the following are valid Python identifiers:

text
1student_name
22students
3total_marks
4student-name
5_user
6class
7age2

Exercise 8: Interactive Mode

Open the Python interpreter and calculate:

python
125 + 75
212 * 8
3100 / 4
42 ** 5

Exercise 9: Automation Practice

Write a loop that prints:

text
1Task 1 completed
2Task 2 completed
3Task 3 completed
4Task 4 completed
5Task 5 completed

Exercise 10: Student Profile

Create your own student profile program using variables, comments, and f-strings.

Quiz

Question 1: Who created Python?

A. James Gosling B. Dennis Ritchie C. Guido van Rossum D. Bjarne Stroustrup

Answer: C. Guido van Rossum

Question 2: Which file extension is normally used for Python source files?

A. .java B. .py C. .cpp D. .js

Answer: B. .py

Question 3: Which function is commonly used to display output?

python
1print()

Question 4: Which symbol starts a single-line comment in Python?

A. // B. /* C. # D. --

Answer: C. #

Question 5: Which is a valid Python variable name?

A. 2name B. student-name C. student_name D. student name

Answer: C. student_name

Question 6: Is Python dynamically typed?

Answer: Yes. Python determines the type of a value at runtime, and variables do not normally require explicit type declarations.

What's Next?

In the next module, you will learn about Python Variables and Data Types in greater detail.

You will explore:

Python's built-in data types
Integers
Floating-point numbers
Strings
Booleans
Lists
Tuples
Sets
Dictionaries
type()
Type conversion
User input
Output formatting

These concepts will help you move from simple Python programs to interactive programs that can process and manipulate real data.