This document discusses the lessons learned from AB testing on a political campaign website. It shows the results of testing different button text and media on key metrics like signups, donations, and engagement. Testing variations of the call to action button increased subscriptions by 40.6% and funds raised by over $57 million. Overall it advocates defining metrics, focusing tests, failing fast from poor performers, and continually testing to find the options with the highest conversion rates. The goal is to use AB testing to continuously optimize the site and improve outcomes.