What is Agile software development

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Agile software development is a conceptual framework for undertaking software engineering projects that embraces and promotes evolutionary change throughout the entire life-cycle of the project.

There are a number of agile software development methods; most attempt to minimize risk by developing software in short timeboxes, called iterations, which typically last one to four weeks. Each iteration is like a miniature software project of its own, and includes all of the tasks necessary to release the mini-increment of new functionality: planning, requirements analysis, design, coding, testing, and documentation. While an iteration may not add enough functionality to warrant releasing the product, an agile software project intends to be capable of releasing new software at the end of every iteration. In many cases, software is released at the end of each iteration. This is particularly true when the software is web-based and can be released easily. Regardless, at the end of each iteration, the team re-evaluates project priorities.

Agile methods emphasize real-time communication, preferably face-to-face, over written documents. Most agile teams are located in a bullpen and include all the people necessary to finish software. At a minimum, this includes programmers and their "customers" (customers are the people who define the product; they may be product managers, business analysts, or actual customers). The bullpen may also include testers, interaction designers, technical writers, and managers.

Agile methods also emphasize working software as the primary measure of progress. Combined with the preference for face-to-face communication, agile methods produce very little written documentation relative to other methods. This has resulted in criticism of agile methods as being undisciplined.

History

The modern definition of agile software development evolved in the mid 1990s as part of a reaction against "heavyweight" methods, as typified by a heavily regulated, regimented, micro-managed use of the waterfall model of development. The processes originating from this use of the waterfall model were seen as bureaucratic, slow, demeaning, and inconsistent with the ways that software engineers actually perform effective work.

A case can be made that agile and iterative development methods are a return to development practice seen early in the history of software development.^[1]

Initially, agile methods were called "lightweight methods." In 2001, prominent members of the community met at Snowbird, Utah, and adopted the name "agile methods." Later, some of these people formed The Agile Alliance[1], a non-profit organization that promotes agile development.

Early agile methods—created prior to 2000—include Scrum (1986), Crystal Clear, Extreme Programming (1996), Adaptive Software Development, Feature Driven Development, and DSDM (1995).

While it was not the first agile method, Extreme Programming (usually abbreviated as "XP") established the popularity of agile methods. Extreme Programming was created by Kent Beck in 1996 as a way to rescue the struggling Chrysler Comprehensive Compensation (C3) project. While that project was eventually canceled, the methodology was refined by Ron Jeffries' full-time XP coaching, public discussion on Ward Cunningham's Portland Pattern Repository wiki and further work by Beck, including a book in 1999.^[2] Elements of Extreme Programming appear to be based on Scrum and Ward Cunningham's Episodes pattern language.

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