In February 2001, 17 people met in Snowbird, Utah, for an exchange and discussion about their ways of software development. They followed different methods and agreed on a list on their shared ideas and the basic thoughts they had in common.

This Agile Manifesto states 4 so-called values:

Individuals and Interactions > Processes and Tools
Working Software > Comprehensive Documentation
Customer Collaboration > Contract Negotiation
Responding to Change > Following a Plan

as well as 12 principles:

  1. Customer Satisfaction
  2. Welcome Changing Requirements
  3. Deliver Frequently
  4. Work together daily
  5. Motivation & Trust
  6. Face-2-face conversation
  7. Working Software
  8. Sustainable Pace
  9. Technical Excellence
  10. Simplicity
  11. Self-organizing Teams
  12. Inspect & Adapt

You can find the unabbreviated version of the Manifesto of Agile Software Development, and some information about the authors. If you agree, you can also sign it.