This document discusses Test Driven Development (TDD), an approach where developers write tests before writing code to satisfy the tests and ensure features function as intended. It was developed in 2003 as part of Extreme Programming (XP) and involves writing a test, seeing it fail, writing code to pass the test, then refactoring code. Benefits include keeping code simple, increasing productivity without debugging, self-documenting code, and designing software with testing in mind from the start.