Agile methods are a family of development processes, not a single approach to software development. In 2001, 17 prominent figures in the field of agile development (then called “light-weight methods”) came together at the Snowbird ski resort in Utah to discuss ways of creating software in a lighter, faster, more people-centric way. They created the Agile Manifesto, widely regarded as the canonical definition of agile development and accompanying agile principles. The Agile Manifesto states:

We are uncovering better ways of developing software by doing it and helping others do it. Through this work we have come to value:

* Individuals and interactions over processes and tools
* Working software over comprehensive documentation
* Customer collaboration over contract negotiation
* Responding to change over following a plan

That is, while there is value in the items on the right, we value the items on the left more.

Some of the principles behind the Agile Manifesto[5] are:

* Customer satisfaction by rapid, continuous delivery of useful software
* Working software is delivered frequently (weeks rather than months)
* Working software is the principal measure of progress
* Even late changes in requirements are welcomed
* Close, daily cooperation between business people and developers
* Face-to-face conversation is the best form of communication (Co-location)
* Projects are built around motivated individuals, who should be trusted
* Continuous attention to technical excellence and good design
* Simplicity
* Self-organizing teams
* Regular adaptation to changing circumstances

The manifesto spawned a movement in the software industry known as agile software development.

In 2005, Alistair Cockburn and Jim Highsmith gathered another group of people—management experts, this time—and wrote an addendum, known as the PM Declaration of Interdependence.

The functioning principles of Agile can be found in lean manufacturing and six sigma. These concepts include error proofing, eliminating waste, creating flow, adding customer value, and empowering workers. The concepts were first formally espoused in the 14 principles of the Toyota Way, the two pillars of the Toyota Production System (Just-in-time and smart automation), the 5S methodology, and Deming’s 14 points. These have been summarized in the seven points of lean software development.