microG GmsCore is a free software reimplementation of Google's Play Services. It allows applications calling proprietary Google APIs to run on AOSP-based ROMs like LineageOS, acting as a free replacement for the non-free, proprietary Google Play Services (sometimes referred to as the more generic term "GApps"). It is a powerful tool to reclaim your privacy and freedom while enjoying Android core features (although apps you use that take advantage of it may still be using proprietary libraries to