Short answer: it’s an open source replacement for Google Play Services, useful for Android modders who run custom ROMs without flashing Google’s proprietary apps and APIs.
Long answer: from the official project page, it’s these five components:
- Service Core (GmsCore) is a library app, providing the functionality required to run apps that use Google Play Services or Google Maps Android API (v2).
- Services Framework Proxy (GsfProxy) is a small helper utility to allow apps developed for Google Cloud to Device Messaging (C2DM) to use the compatible Google Cloud Messaging service included with GmsCore.
- Unified Network Location Provider (UnifiedNlp) is a library that provides WiFi and cell-tower-based geo-location to applications that use Google’s network location provider. It is included in GmsCore but can also run independently on most Android systems.
- Maps API (mapsv1) is a system library, providing the same functionality as now deprecated Google Maps API (v1).
- Store (Phonesky) is a front-end application providing access to the Google Play Store to download and update applications. Development is in early stages and there is no usable application yet.
If an open source interface for Google’s app store seems somewhat contradictory, consider the promising YouTube replacement NewPipe, which offers access to the same videos but removes the annoying pre-roll ads.
The microG project was first announced on XDA over two years ago, but just got a lot easier to install; there is now an unofficial build of LineageOS with microG services built-in. Device support is impressive to say the least—I’m guessing that the builds are automated from the official Lineage device tree.
With their completely unnecessary vendor image Google has already ruined their phone hardware for me; should the day ever come for me to wean myself off of Gmail and the like my fallback position would most likely be the F-Droid app store and an Android custom ROM. I’ve never actually tried it, though, and I honestly hadn’t considered just how deeply integrated Google Mobile Services were in a typical Android device.
Love Android but hate Google? microG is here to help.