How is Error.cshtml called in ASP.NET MVC?

I've read a dozen similar questions on StackOverflow, but I can't seem to grasp this. With regards to the custom errors node in the web.config and the HandleErrorAttribute, how does the Error.cshtml ever get called? Ultimately the answer to this question may be the answer to one of those several questions already out there regarding ASP.NET MVC error handling. But, fact of the matter is, I don't know which one.