The URI fragment makes single-page web apps possible. It removes the waste of having the browser re-parse DOM and re-interpret Javascript each time the user swi

The URI fragment makes single-page web apps possible. It removes the waste of having the browser re-parse DOM and re-interpret Javascript each time the user switches interfaces. One disadvantage is that the Referrer header does not include the fragment identifier. But that's a problem with the Referrer header and not necessarily the fragment identifier. The fragment identifier has been a part of the web for years, for the purpose of describing the user's state on the client. It's just that we interpreted this as just meaning "bookmarks" and didn't use it for anything more than that. We've only recently started to understand the fragment identifier and use it more fully.