title: Why do we use nullable string in C#?
body: <p>In Microsoft official Learning Module &quot;Create a Web API with ASP.NET Core&quot; Why some sample codes use nullable string type although we know strings are nullable in itself since it is a reference type?
  See Model/Pizza.cs class in this <a href="https://docs.microsoft.com/en-us/learn/modules/build-web-api-aspnet-core/5-exercise-add-data-store" rel="nofollow noreferrer">tutorial</a>.</p>