Variables & Assignment

Introduction

In Python, variables are names bound to objects, not boxes that hold values. You don't declare types — Python infers them at runtime.

Understanding the topic

Core concepts to understand:

• x = 42 binds the name x to an int object.
• Reassignment changes the binding, not the object.
• Multiple assignment: a, b = 1, 2.
• Constants by convention: UPPER_CASE.

Syntax reference

Visual flow / code:

name = "Alice"
age = 30
is_admin = True

# Multi / swap
a, b = 1, 2
a, b = b, a   # swap

# Type hints (optional but recommended)
score: int = 100

Execution workflow

Real-world use

Type hints, added in Python 3.5, are now standard in production code — they enable mypy, IDE autocomplete, and self-documenting APIs.

Best practices

• Use snake_case for variables.
• Add type hints on public functions.
• Avoid 1-letter names except in loops.

Hands-on exercise

Interview preparation — practice these questions:

• Is Python statically or dynamically typed?
• What's the difference between = and ==?
• What are type hints?

Summary

In summary: Names → objects, not boxes. Type hints = production hygiene.