The Agile SEO Cycle is a method for performing SEO that is quick, efficient, and accounts for constant changes. It involves 7 steps: 1) Discovering a site's purpose and metrics; 2) Analyzing the site; 3) Strategizing an optimization plan; 4) Executing the strategy; 5) Measuring impacts; 6) Reporting results to clients; and 7) Adjusting for weaknesses and building on successes. The goal is to continuously improve SEO through this repeating cycle as search engines evolve.