Agile Manifesto

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

The Manifesto for Agile Software Development is based on twelve principles:

Customer satisfaction by early and continuous delivery of valuable software
Welcome changing requirements, even in late development
Working software is delivered frequently (weeks rather than months)
Close, daily cooperation between business people and developers
Projects are built around motivated individuals, who should be trusted
Face-to-face conversation is the best form of communication (co-location)
Working software is the primary measure of progress
Sustainable development, able to maintain a constant pace
Continuous attention to technical excellence and good design
Simplicity—the art of maximizing the amount of work not done—is essential
Best architectures, requirements, and designs emerge from self-organizing teams
Regularly, the team reflects on how to become more effective, and adjusts accordingly

Additional Resources

Agile Software Development
Extreme Programming
The Agile Manifesto
Waterfall Method