Conversation

A "back to top" button is an interface design element used only and exclusively on web sites. Do large text documents have it? No! Do books have it? No!

The only thing that comes close is the "rewind" button on movie and music players.

They were invented during a time when all computer users had keyboards with a Home button: the original "back to top". That home button is why large text documents don't need a separate button.

Mobile devices with no home button had yet to get popular.