How to Install Python and Run Your First Program 2026

Installing Python

Download Python from the official website python.org/downloads. Always download the latest stable Python 3 release.

Go to python.org/downloads and click "Download Python 3.x.x"
Run the installer - check "Add Python to PATH" before clicking Install
Verify installation by opening a terminal and running:

Verify Installation

python --version
# Python 3.12.0

python3 --version   # on macOS/Linux
# Python 3.12.0

Choosing an IDE / Editor

Editor	Best For	Notes
VS Code	General development	Free, lightweight, great Python extension
PyCharm	Professional Python	Full-featured IDE, free Community edition
Jupyter Notebook	Data Science	Interactive, great for exploration
IDLE	Beginners	Comes bundled with Python
Thonny	Absolute beginners	Simple, shows variable values visually

Running Python Code

There are three ways to run Python code:

1. Interactive Mode (REPL)

Type python in your terminal to open the interactive shell. Great for quick experiments.

Python REPL

>>> print("Hello, World!")
Hello, World!
>>> 2 + 3
5
>>> name = "Alice"
>>> print(f"Hello, {name}!")
Hello, Alice!

2. Script File

Create a .py file and run it with python filename.py.

First Python Script

# main.py
print("Hello, World!")

# Get user input
name = input("Enter your name: ")
print(f"Hello, {name}! Welcome to Python.")

# Basic arithmetic
a = 10
b = 3
print(f"{a} + {b} = {a + b}")
print(f"{a} / {b} = {a / b:.2f}")

Python Indentation

Unlike most languages, Python uses indentation (whitespace) to define code blocks - not curly braces. This is mandatory, not optional.

IndentationError: Inconsistent indentation will cause your program to crash. Use 4 spaces (or a tab) consistently.

Indentation Rules

# Correct indentation
if True:
    print("This is indented correctly")   # 4 spaces
    if True:
        print("Nested block")             # 8 spaces

# Function with indented body
def greet(name):
    message = f"Hello, {name}!"
    return message

# This would cause IndentationError:
# if True:
# print("Missing indent")  # ERROR!

Python File Structure

A typical Python project looks like this:

Project Structure

my_project/
├── main.py           # Entry point
├── utils.py          # Helper functions
├── requirements.txt  # Dependencies
├── README.md         # Documentation
└── tests/
    └── test_main.py  # Unit tests