Use this tag for questions about the agile methodology, which describes a set of principles for software development.
Before using this tag it is recommended to review Project Management Stack Exchange or Software Engineering Stack Exchange, questions specifically about agile may get a better response on these sites.
From Wikipedia:
Agile software development describes a set of principles for software development under which requirements and solutions evolve through the collaborative effort of self-organizing cross-functional teams. Based off Agile Architecture, it advocates adaptive planning, evolutionary development, early delivery, and continuous improvement, and it encourages rapid and flexible response to change. These principles support the definition and continuing evolution of many software development methods.
