Extreme Programming XP improves the efficiency of writing software. This is accomplished by streamlining complexity, delivering top business value early and consistently, and reducing the cost of nearly inevitable changes to the business rules, programming environment, or software design. Many of these practices have been part of conventional wisdom for years, but rethinking their interaction is the value of XP.

Website: http://linuxdevcenter.com/pub/a/linux/2001/05/04/xp_intro.html