# Recursion
Confidence: high
Last verified: 2026-05-22
Generation: human_only


## TL;DR

Recursion is a technique where a function calls itself to solve smaller instances of the same problem. It requires a base case (termination) and recursive case (problem reduction). Recursion elegantly models tree traversal, divide-and-conquer, and backtracking.

## Core Explanation

Tail recursion: recursive call is the last operation — compilers can optimize to iteration (no stack growth). JavaScript engines (Safari JSC only) support TCO. Recursion depth limited by call stack (~10K in browsers). Recursion can always be converted to iteration (using explicit stack), and vice versa.

## Further Reading

- [Structure and Interpretation of Computer Programs (SICP)](undefined)