When developing with the Sitecore ASP.

 When developing with the Sitecore ASP.NET Core Rendering SDK, you need to register component renderers within the rendering host’s Startup.cs class to map a Sitecore rendering component name to an implementation. This allows the Sitecore Rendering Engine to render the content fetched from the Sitecore Layout Service using the appropriate component renderer. For example, you can map a Sitecore layout component name to a view component rendering or a partial view rendering. You can use the AddViewComponent() and AddPartialView() extension methods to register component renderers in the Startup.cs class. References:

[Sitecore 10 .NET Developer Certification Study Guide], page 18

Sitecore Documentation: Sitecore Rendering Engine