Syntax & Indentation

Introduction

Python uses indentation, not braces, to define code blocks. This forces consistent formatting and is one of the most distinctive features of the language.

Understanding the topic

Core concepts to understand:

• 4 spaces per indent (PEP 8).
• Colons start blocks: if, for, def, class.
• Comments use #; docstrings use """...""".
• Statements end at line break — no semicolons.

Syntax reference

Visual flow / code:

def factorial(n: int) -> int:
    """Return n! using recursion."""
    if n <= 1:
        return 1
    return n * factorial(n - 1)

# Multi-line: use parens or backslash
total = (
    1 + 2 + 3
    + 4 + 5
)

Execution workflow

Real-world use

Indentation-based syntax is divisive but enforces readable code — there's only one way to format a block, which kills bikeshedding in code reviews.

Best practices

• Always 4 spaces, never tabs.
• Configure your editor for PEP 8.
• Add docstrings to public functions.

Common mistakes

• Mixing tabs and spaces — Python 3 errors out.
• Inconsistent indent depth.

Hands-on exercise

Interview preparation — practice these questions:

• Why does Python use indentation?
• What's PEP 8?
• Tabs vs spaces?

Summary

In summary: Indentation defines structure. PEP 8 = community style law.