An Agile software development methodology that emphasizes customer involvement, transparency, testing and frequent delivery of working software.
The Extreme Programming canon includes a Customer Bill of Rights and a Developer Bill of Rights, and lists its core values as communication, simplicity, feedback, courage and respect. XP is a developer-centric methodology, and unlike Scrum, it prescribes specific coding practices like Pair Programming, in which two developers work side by side at a single machine, automated unit testing, and frequent integration. Another key practice in XP is refactoring, or the continual improvement of design over many iterations.
The basic advantage of XP is that the whole process is visible and accountable. The developers will make concrete commitments about what they will accomplish, show concrete progress in the form of deployable software, and when a milestone is reached they will describe exactly what they did and how and why that differed from the plan. This allows business-oriented people to make their own business commitments with confidence, to take advantage of opportunities as they arise, and eliminate dead-ends quickly and cheaply. — Kent Beck
In 1996, Chrystler’s visionary CIO, Sue Unger, gave Kent Beck free reign to form a team to tackle the Chrystler Comprehensive