Everything you need to know about Android’s Project Mainline
One of the biggest changes in Android in recent years that flew under the radar, relatively speaking against its importance, was the introduction of Project Mainline in Android 10. Google mandates the inclusion of specific Mainline modules across Android releases, with Android 11 coming in with a combined compulsory total of 25 Mainline modules. Here is an explanation on what Project Mainline is and what it aims to solve, alongside a list of all of Android's Project Mainline modules.
A great overview of this very important, relatively new part of Android.