Getting Started with Python

Python · Reference cheat sheet

📋 Overview

Python is a readable, general-purpose language used for scripting, web backends, data work, and automation. You write .py files (or use the interactive REPL) and run them with the python (or python3) interpreter.

🔧 Core concepts

Install check: open a terminal and run python --version (or python3 --version). Use a virtual environment (venv) so project packages stay isolated.

Typical first workflow:

1. Install Python 3 from python.org (or your OS package manager).
2. Create a folder for practice files.
3. Write hello.py, then run python hello.py.

💡 Examples

Check the version:

python --version
# Python 3.12.x

Start the REPL:

python

>>> 2 + 2
4
>>> print("hi")
hi
>>> exit()

Create and run a script:

# hello.py
print("Hello from a file!")

python hello.py

Create a virtual environment (recommended):

python -m venv .venv
# Windows PowerShell:
.\.venv\Scripts\Activate.ps1
# macOS/Linux:
source .venv/bin/activate
pip install requests

⚠️ Pitfalls

• On some systems python is missing and you must use python3.
• Mixing system Python and project packages without venv causes version conflicts.
• Indentation is syntax in Python — tabs vs spaces can break files.
• Saving as .txt or wrong encoding can confuse beginners; use UTF-8 .py files.

🔗 Related

• hello_world.md
• variables.md
• comments.md
• indentation.md
• venv.md · pip.md