🧩 3. Iterative Deepening
Engine searches in layers:
Depth 1 → Depth 2 → Depth 3 → … → Depth N
✔ Analogy
Imagine reading the summary of a book first, then reading deeper chapters one by one.
✔ Why engines do this
- Ensures a valid move is always available if time runs out
- Helps ordering moves better (critical for pruning)
- Reuses information from shallow searches to speed up deeper searches
✔ How it works
At depth 1, it sees only captures/checks.
At depth 20, it sees extremely accurate long-term tactics.