## TL;DR

Pair programming (part of XP, Kent Beck) is two developers working at one computer: Driver (writes code) + Navigator (reviews each line, thinks strategically). Roles switch frequently. Studies show 15% more effort but 15% fewer defects — net quality improvement. Extremely effective for complex problems and knowledge transfer.

## Core Explanation

Styles: Driver-Navigator (one codes, one reviews), Ping-Pong (TDD: one writes test, other makes it pass), Strong-Style (novice drives, expert navigates — for knowledge transfer). Benefits: continuous code review, knowledge sharing, better design (two minds), reduced distractions. Not effective for: simple/mechanical tasks, when developers can't get along.

## Further Reading

- [Extreme Programming Explained (2nd Ed, Kent Beck)](undefined)