Values determine what is important. XP’s values guide its practices. Being clear on what the values on a project can help reduce the waste results from different members pursuing different values.
In the first edition of Extreme Programming Explained, Kent Beck described XP as having 4 values: Communication, Simplicity, Feedback and Courage. In the second edition, he added a fifth one : Respect. XP doesn’t see these values as exhaustive though – depending on the context projects, projects can have additional values considered important – for example Safety, Predictability , Security and so on.