Python Basics — Control Flow

Control Flow

Programs rarely run straight from top to bottom. Control flow statements let you make decisions — running different code based on conditions.

This chapter covers every way Python lets you branch your code.

What You’ll Learn

Topic	Description
if/elif/else	Basic conditional branching
Nested Conditions	Decisions inside decisions
Ternary Operator	One-line conditional expressions
Match-Case	Structural pattern matching (3.10+)
Truthy & Falsy	How Python evaluates truth
Practice Exercises	Test your skills

Why Control Flow Matters

Without control flow, your programs would always do the same thing regardless of the input. Control flow gives your code the ability to:

• Make decisions — “If the user is logged in, show the dashboard”
• Handle different cases — “If the file exists, read it; otherwise, create it”
• Validate input — “If age is negative, show an error”
• Branch logic — “Grade based on score: A, B, C, D, or F”

Quick Preview

age = 18

if age >= 18:
    print("You can vote!")
elif age >= 16:
    print("Almost there!")
else:
    print("Too young to vote.")

Output:

You can vote!

Control flow is one of the most fundamental concepts in programming. Once you understand it, you can write programs that actually respond to the real world.

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