What Do We Know about Agile Software Development?

Agile software development has had a huge impact on how software is developed worldwide. We can view agile methods such as Extreme Programming (XP) and Scrum as a reaction to plan-based or traditional methods, which emphasize a "rationalized, engineering-based approach, incorporating extensive planning, codified processes, and rigorous reuse. In contrast, agile methods address the challenge of an unpredictable world, emphasizing the value competent people and their relationships bring to software development. To clarify the effectiveness of agile methods, we reviewed the agile development literature and conducted a systematic study of what we know empirically about its benefits and limitations.