Agile is a SOFTWARE development model that has an iterative approach for software development that helps teams to deliver value to their customers faster, with greater quality, with lesser errors, greater ability to respond to change.
An agile team delivers a product in small increments instead of a “BIG bang” launch. Requirements, plans, and result evaluation is continuously DONE, so teams have a NATURAL mechanism for a quick response to change.
Scrum and Kanban are the most frequently USED Agile methodologies.