Development and quality assurance

The development part of this phase probably requires the least explanation: it's when the actual code gets written, using the defined requirements to determine what the goals of the code are, and the architecture/design to determine how to write the code. An argument could probably be made that the quality assurance part of this phase should be broken out into its own grouping, if only because many of the activities involved are substantially different—there's less code authoring going on, if there is any at all, in executing a manual test plan, after all. That said, the concept of automated testing, which may be able to replace a lot of the old-style manual test plan execution activities, does require a substantial amount of code, at least at first. Once those test suites are established, regression testing becomes much simpler and less time-consuming. Development methodologies' concerns with the QA aspects of this phase are usually centered around when QA activities take place, while the actual expectations of those activities are usually a combination of development standards and best practices.