Extreme Programming (XP) is a discipline of software development with（ 1 ）of simplicity, communication, feedback and courage. Successful software development is a team effort - not just the development team,but the larger team consisting of customer, management and developers. XP is a simple process that brings these people together and helps them to succeed together. XP is aimed primarily at object-oriented projects using teams of a dozen or fewer programmers in one location. The principles of XP apply to any（ 2 ）project that needs to deliver quality software rapidly and flexibly.

An XP project needs a（ 3 ）customer to provide guidance. Customers, programmers, managers, are all working（ 4 ）to build the system that's needed.Customers - those who have software that needs to be developed-will learn simple, effective ways to（ 5 ）what they need, to be sure that they are getting what they need, and to steer the project to success.