It’s a well-known fact that Android is for all purposes and purposes of open-source software. This means that anyone with the know-how can modify or sell the software, and Google can not do much about it. But the search giant continues to control the platform by other means. By other means, I mean Google Play Services. Google believes in free software, not free services. And Google Play services are how Google makes dollars from a free software platform. Some open-source enthusiasts do not like Google’s control over Android, because without Google’s services, the platform is basically outdated. Android uses Google Play Services for virtually every smart thing it does just down to push notifications from apps. This is why microG aims to cut off Google.
With all the talk about privacy concerns recently, Google's name keeps coming up because they are a very data-driven company. As an Android user, they know basically everything about you based on your device usage, and that can scare some people off who are worried about their privacy and security. You do have some say in what personal data Google controls, but what if you wanted even more?
You should note that many apps require Google Play Services to work correctly; otherwise, there would be no point in having them installed. MicroG injects a modified version of those core Google services required by most apps, but without all of the tracking or any extra Google apps and background services. This increases your level of privacy and can even improve battery life.
What is microG?
MicroG is an open-source replacement for Google Play Services on devices running Android. Since Google Play Services form a large part of the backbone of Android (many apps use the services), it is a very helpful piece of software for people going NO GAPPS. It is developed almost solely by Marvin W, user MaR-V-iN on the XDA Forums. It is very much a work in progress, though it is plenty stable for everyday use and the core functionality is in place: location services, Google authentication, and Google Cloud Messaging, which many apps use for notifications.
MicroG is an open-source replacement for Google Play Services on devices running Android. ... It is very much a work in progress, though it is plenty stable for everyday use and the core functionality is in place: location services, Google authentication, and Google Cloud Messaging, which many apps use for notifications.
This project is “a free software clone of Google’s proprietary core libraries and applications”. To be more specific, it is a FLOSS (Free / Libre Open Source Software) box that allows apps designed for Google Play services to run on systems where Play Services is unavailable. It provides all the necessary APIs provided by Google Play services so that
apps that depend on it can run normally.