Agile methods of software development provide ways of creating software in a lighter, faster, more people-centric way. The definition of agile development and agile principles, according to the “agile manifesto”, is as follows:

Valuing individuals and interactions over processes and tools Valuing working software over comprehensive documentation Valuing 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 are: Customer satisfaction by rapid, continuous delivery of useful software Working software 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. For more about agile software systems and development, you might want to visit this article on agile software.