The document discusses the history and benefits of test-driven development (TDD). It notes that practices like agile development, extreme programming, and open source helped popularize TDD. TDD emphasizes writing tests before code, continuous integration, refactoring, loose coupling, and testing all new code. The document acknowledges research showing TDD may take longer initially but finds fewer bugs. It provides examples of Ruby testing tools and frameworks that facilitate TDD. The overall message is that the software development community now widely accepts and uses TDD.