Python Cheat Sheet (2026): Syntax, Types, Functions & Comprehensions

A Python cheat sheet covers indentation-based blocks, dynamic types with optional hints, functions, lists/dicts, and comprehensions. In 2026 you still run CPython 3.12+ with venv, f-strings, and pathlib. This sheet is language core — not a Django manual.

This Python cheat sheet is written for people searching for a fast, accurate reference: students, junior developers, and teams shipping production software. Pin it, copy the snippets, and come back when syntax slips.

Quick reference

• Indent: Blocks are whitespace. Four spaces. No braces.
• Assign: x = 1. Unpack a, b = b, a.
• Types: int, float, bool, str, list, dict, None. Hints: def f(x: int) -> str:.
• f-string: f"Hello {name}". = debug: f"{n=}".
• List / dict: [1, 2], {"k": "v"}. Comprehensions: [x*2 for x in nums if x > 0].
• Functions: def greet(name: str = "there") -> str: plus *args, **kwargs.
• venv: python -m venv .venv then pip install. Do not install to system Python.
• Main: if __name__ == "__main__": for scripts.

Copy-paste examples

Comprehension, f-string, and a typed helper

Prefer comprehensions for map/filter of small lists. Name a function when the expression grows.

from typing import Iterable

def slugs(titles: Iterable[str]) -> list[str]:
    return [t.strip().lower().replace(' ', '-') for t in titles if t.strip()]

def greet(name: str, excited: bool = False) -> str:
    mark = '!' if excited else '.'
    return f'Hello {name}{mark}'

if __name__ == '__main__':
    print(greet('Humza'), slugs([' PHP 8 ', 'SQL']))

Common mistakes

• Mixing tabs and spaces until IndentationError on another machine.
• Using Python 2 print statements from old blogs.
• Mutating a default def f(x=[]) — the list is shared across calls.
• Catching Exception empty and hiding bugs in scripts.

FAQ

1. Python vs PHP for the web? Both work. PHP is typical on shared hosting/XAMPP. Python is common for APIs, data, and Django/Flask. Pick by team and host.

1. Do I need a type checker? Hints are optional at runtime. mypy or Pyright catch mistakes. Start with hints on public functions.

1. What is pip? The package installer. Pin versions in requirements.txt or use Poetry/uv for apps.

Related Python cheat sheets

• Python Data Types Strings Cheat Sheet
• Python Lists Dictionaries Cheat Sheet
• Python Functions Oop Cheat Sheet

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