The granddaddy of them all, there is no self-respecting agile book that doesn't reference these in some way.

The original is at http://agilemanifesto.org and is best read there. Following list is maintained for my convenience.

The Values are:

• 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 Principles are:

• Our highest priority is to satisfy the customer through early and continuous delivery of valuable software.
• Welcome changing requirements, even late in development. Agile processes harness change for the customer's competitive advantage.
• Deliver working software frequently, from a couple of weeks to a couple of months, with a preference to the shorter timescale.
• Business people and developers must work together daily throughout the project.
• Build projects around motivated individuals. Give them the environment and support they need, and trust them to get the job done.
• The most efficient and effective method of conveying information to and within a development team is face-to-face conversation.
• Working software is the primary measure of progress.
• Agile processes promote sustainable development. The sponsors, developers, and users should be able to maintain a constant pace indefinitely.
• Continuous attention to technical excellence and good design enhances agility.
• Simplicity–the art of maximizing the amount of work not done–is essential.
• The best architectures, requirements, and designs emerge from self-organizing teams.
• At regular intervals, the team reflects on how to become more effective, then tunes and adjusts its behavior accordingly.

• Agile Manifesto
• Principles Behind the Manifesto
• Authors of the Manifesto
• History of the Manifesto
• Book Understanding Agile Values & Principles. An Examination of the Agile Manifesto - By Scott Duncan