⬇️ Top-Down Design

Step 1: Build individual small components \u2014 play button, volume slider, like button, etc.
Step 2: Combine related components into modules \u2014 play button + volume + progress bar = Video Player
Step 3: Combine modules into the complete system \u2014 Video Player + Video Page + Search = YouTube App

📖 Definition

Top-down design starts with the overall problem and progressively breaks it into smaller, more manageable sub-problems. You keep breaking things down until each piece is simple enough to solve directly.

Also called stepwise refinement or decomposition.

🎮 Example: Building a Fortnite Game

🔍 The Process

Level 1: Start with the whole problem — "Build Fortnite"
Level 2: Ask "what are the major parts?" — Player System, Battle System, Map System
Level 3: Ask "what does each part need?" — Player System needs Login and Inventory, etc.
Keep going until each piece is simple enough to code directly

🎯 Exam Tip

Top-down design goes from general → specific. The keyword to remember is decomposition — breaking a problem into smaller sub-problems. Structure charts (from Lesson 08) are a top-down design tool.