In consultation with the customer or product owner, the team divides up the work to be done into functional increments called "user stories."| Agile Alliance |
Refactoring consists of improving the internal structure of an existing program's source code, while preserving its external behavior.| Agile Alliance |
An iteration is a timebox during which development takes place. The duration may vary from project to project and is usually fixed.| Agile Alliance |
Test-driven development (TDD) is a style of programming where coding, testing, and design are tightly interwoven. Benefits include reduction in defect rates.| Agile Alliance |