XP has four main values: communication, feedback, simplicity, and courage. All of XP’s practices support these values.
Good communication is essential to any project. Honest, regular communication allows you to adjust to change. This is how developers know what to do and how the customer knows when it will be done. Hiding or ignoring information can sink your project.
XP asks people in business roles to make business decisions and people in technical roles to make technical decisions. Customers answer the questions “What will be done?” and “What are the priorities?” Developers answer the questions “How will this be accomplished?” and “How long will each step take?” Developers trust the business people to identify features and their priorities, because they know the problem domain. Business people trust the developers to identify and to estimate the work that must be done, because they know the technology. Each group takes responsibility for its own decisions. Both groups are part of the same team, devoted to meeting the customer’s needs.
XP puts developers and customers in constant communication. A customer works with you to set business priorities and to answer questions. The customer must analyze the project both as a real user and from a business point of view. The customer sees the team’s progress every day and can adjust the work schedule as needed. The customer works with developers to produce tests to verify that a feature is present and works ...