XP - Extreme Programming
Extreme Programming (XP) is the second most popular framework, used by roughly 10% of Agile teams. XP stands out as one of the few Agile frameworks that prescribe technical practices.
Background
The following timeline shows a brief history of Extreme Programming (XP):

The 1990s was the beginning of another paradigm shift for the software industry as Object-Oriented Programming began to replace Structured Programming. As a way to explore how they would use this new approach, the Chrysler motor company decided to build their payroll system in Smalltalk, an OO programming language.
Initially invited to performance-tune the system because of his knowledge of Smalltalk, Kent Beck was asked to lead their software team in 1996. In Kent's potted history of XP, he says that, before joining Chrysler, he had asked teams to do things he thought were important, such as testing and reviews. This time, at Chrysler, he felt there was a lot more at stake, so Kent asked the team to turn...