Is REST only for Web APIs? If not, then what other systems can obey REST apart from Web APIs?

Question

I hear people say as per Roy Feilding that REST is not just for web services. If so, what other systems/mechanisms/anything can use it?

Answer 1

Any system that uses URIs to communicate information would be able to use REST.

Example: a theoretical database that fully follows REST rules.

Example resource "serverhost/database/table/1"