AGILE is a set of methods and practices based on the values and principles of the Agile Manifesto, which have ben derived as follows:
The highest priority is customer satisfaction through early and continuous delivery of the project.
Welcome changing requirements, even late into development. Agile processes harness change for the customer's competitive advantage.
Deliver working projects frequently with preference to shorter timescales.
Business people and developers should collaborate on a daily basis.
Build the project around motivated individuals, providing them the environment and support needed and trusting them to complete tasks.
The most efficient and effective method of conveying information to and within a team is face-to-face conversation.
Working projects are the primary measure of success.
Agile processes promote sustainable development. Everyone should be able to maintain a constant pace indefinitely.
Continuous attention to technical excellence and good design enhances agility.
Simplicity - the art of maximising the amount of work not done - is essential.
The best architectures/designs/requirements emerge from self-organising teams.
At regular intervals, the team reflects on how to increase effectiveness and adjusts their behaviours accordingly.
SCRUM is an agile framework - one of the most popular. It focuses on working on bunches of tasks in sprints, getting together for reviews of progress, and repeating the process.