In 2001, 17 established individuals met at Snowbird Ski resort in Utah to come up with a lightweight software development methodology as against the heavyweight tradition waterfall method. They came up with the Agile manifesto(1) that 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."
You can read complete history about the Manifesto at The Agile Manifesto(1)