The road to .NET 6
This part of the book is about the functionality in the Base Class Library (BCL) APIs provided by .NET and how to reuse functionality across all the different .NET platforms using .NET Standard.
First, we will review the route to this point and why it is important to understand the past.
.NET Core 2.0 and later's support for a minimum of .NET Standard 2.0 is important because it provides many of the APIs that were missing from the first version of .NET Core. The 15 years' worth of libraries and applications that .NET Framework developers had available to them that are relevant for modern development have now been migrated to .NET and can run cross-platform on macOS and Linux variants, as well as on Windows.
.NET Standard 2.1 added about 3,000 new APIs. Some of those APIs need runtime changes that would break backward compatibility, so .NET Framework 4.8 only implements .NET Standard 2.0. .NET Core 3.0, Xamarin, Mono, and Unity implement...