When I presented my topic at ISPI’s THE Performance Improvement Conference in 2014, I was prepared to share my ideas with colleagues about the nuances of Agile to buttress comparisons with the standards and principles of human performance technology (HPT). What my audience that day wanted was the basics of Agile. They asked me, in a dozen different ways, "What the heck is Agile?" This chapter provides an introduction to Agile software development and direction for those who want to explore further. If you are already well into your Agile journey, I have a few tidbits for you as well.