Visual Studio 2017 provides you with an easy and comfortable way to build a NuGet package for .NET Standard libraries. .NET Standard Library is a formal specification of the .NET APIs, which are intended to be available on all .NET runtimes. .NET Standard Library defines a uniform set of Base Class Library (BCL) APIs for all the .NET platforms, and enables developers to produce portable class libraries that can run in all .NET runtimes.

Let's first create a .NET Standard class library. Create a new project by selecting Class Library (.NET Standard) under the Visual C# | .NET Standard templates, as shown in the following screenshot. Give it a proper name, select the location where you want to create the project, and hit OK:

Once the project gets created, create the class files that you want to bundle with your package and write the necessary code. Build your project in Release mode to make sure there are no errors.