XP's twelve practices are derived from the four values.
Test Driven Development.
Unit tests written before and during coding allow rapid change by providing confidence that errors aren't creeping into the product.
Small releases help ensure that the developers and customers are able to provide each other with continuous feedback.
Refactoring allows the design to be continually enhanced and simplified over time by reducing redundancy and complexity.
Reducing complexity is just as important as coding.
Only plan enough to get started and refine the plan after every release.
All production code is written by two people collaborating at the keyboard. This enables collective code ownership and helps to catch coding problems as early as possible.
An onsite customer ensures that feedback is nearly instantaneous so no time is wasted waiting.
A common real-world metaphor that is understood by customers, developers, and managers is used for elements of the project.
Collective Code Ownership.
Collective code ownership helps ensure that no one team member is the critical path or sole repository of knowledge on a particular section of code.
Changes are placed into the shared version control system as early and often as possible so that every developer is working from the latest version of the software. This helps to ensure that problems are caught as early as possible.
Consistent coding conventions aid communication within the team and reduce the amount of time required to learn a new section of code.
Work at a consistent pace so that consistent and accurate estimates can be made. Use a 40-hour work week to ensure there is also a balance between home and work.