Maintenance

Maintenance is really the normal state of an XP project. You have to simultaneously produce new functionality, keep the existing system running, incorporate new people into the team, and bid farewell to members who move on.

Every release begins with an exploration phase. You may try big refactorings that you were afraid of late in the previous release. You may try new technology that you intend to add in the next release, or migrate to newer versions of the technology you are already using. You may experiment with new architectural ideas. The customer may try writing wacky new stories in search of a big winner for the business.