In the context of the OWIN Framework presentation refers to any middleware that sits at the end of the OWIN pipeline and generates a response to be sent back to the client. In general presentation middleware will not pass on requests to the rest of the OWIN pipeline for further processing unless the url represents a non-existent resource, in which case it makes sense to configure middleware behind the presentation middleware that always returns a 404 (Not Found) response.

Some examples of typical presentation middleware are: MVC or MVVM frameworks, REST services, static file handlers, media servers.