Agile methodology involves iterative development and testing. It emphasizes incremental and evolutionary development by breaking projects into smaller pieces that are integrated for testing. Popular Agile frameworks include Scrum, Kanban, Extreme Programming, Crystal, Dynamic Systems Development Method, and Feature-Driven Development. The Agile Manifesto outlines core values and principles of Agile, including prioritizing individual/interactions over processes/tools and customer collaboration over contract negotiation.