- XP values are widely applicable.
- XP principles may need to be modified across different domains.
- XP practices are very situation dependent. They may need to be modified to fit a given project situation. Not all practices may fit your project. Teams new to XP can try them out and see which do. An XP practice is a theory or prediction of an activity that should make the project more productive.
Kent Beck divided XP Practices into primary practices (foundational XP practices can be applied to a project straight away) and corollary practices (which build on the mastery of the primary practices).