One of the great things about .NET is that you use it to write code for multiple runtimes, such as .NET Core, .NET Framework, and Xamarin. But multiple runtimes mean some complexity in writing, distributing, and consuming libraries. .NET Standard solves this problem.
.NET Standard 2.0 is the latest version of .NET Standard. Watch this video to learn about how to get started with .NET Standard 2.0.
.NET Standard is a formal specification to build .NET based libraries and APIs for all .NET versions. Learn more here What is .NET Standard.