No GAPPS is a movement largely in response to privacy concerns involving Google’s business practices, though some also take part because they find that Google’s proprietary Play Services is a large cause of battery drain on their Android phones. The idea is to avoid using Google services (i.e. Hangouts, Google Plus, Google Play, etc.) and finding alternatives that are FOSS and/or privacy-friendly. To maintain compatibility with Google services on their Android devices (as Android is developed by Google), some use the open-source alternative to Play Services called microG.