title: Add Reference to dll vs. adding a NuGet package in .NET Standard project
body: <p>I have a .NET Standard 2.0 project in my solution and I am using the IConfiguration interface. When I write the name VS suggest that I reference Microsoft.Extensions.Configuration.Abstractions.dll. If I do it is added under the reference node. However I can also add it as a NuGet package. Both ways seems to work. I assume that the reference VS suggests is added via the .NET Standard SDK that is referenced in the project.</p>
  
  <p>Which is the recommended way to add that reference? What are the advantages and the disadvantages of each approach?</p>