Android is the operating system that runs on all android phones (just like how iOS runs on all iphones) Google codenames each major update alphabetically with desserts (you can do a quick wikipedia search to see how it started). Therefore, jelly bean (the latest OS) is android version 4.2.x. When google jumps to version 5.0 itll be code named with a dessert starting with a "K" and the current rumor is Key Lime Pie. We will find out in 2-3 months. Hope this helps.