When you create a web API, documenting its capabilities for the consuming developers can be a task if you take it on manually. Swagger gives you the ability as the API developer to add self-documenting helper pages and test harnesses to your API.
Recently John and I took some time away to discuss how to use Swagger to document a Web API written in ASP.NET Core using Swashbuckle and Visual Studio for the Mac
Here is the result of that conversation. Check out the Play by Play on Pluralsight