(All My Notes are attributed/sourced from the Resources directly preceding them.)
Summary
Xamarin Essentials attempts to address the most common needs of developers.
Connectivity
Device Information
Geolocation
Secure Storage
Version Tracking
Xamarin.Essentials is the library that handles this within Visual Studio and it has been fine tuned to not bloat the applications using it no matter how many features are used.
Resources
Accessing Native Features the Cross-Platform Way with Xamarin.Essentials
Author: James Montemagno (Microsoft Xamarin DevBlogs)