So I was typing along in Microsoft Word on a Mac, when all of a sudden I was writing over all of the text -- as if I had pressed the Insert key on a PC. Nothing is listed on any of the menus, or when I searched the help field (that's because the Mac calls it "overtype," which I didn't know at the time).

At the very bottom of the document's screen, there are some bits of information (page, section, total number of pages, etc.). On the far right, there are four abbreviated words: REC TRK EXT OVR, each with a small circle to their left. If you click the OVR word, its circle will turn green and you will write over text until you again click the OVR box.

I searched and searched online and couldn't find info because the word -- overtype -- was not in my personal vocabulary, so I didn't search for it.

[robg adds: Yes, this is a simple hint on a somewhat-obvious feature. But it's one that I actually get asked a fair bit by PC switchers, as the Mac doesn't have an Insert key as such (the Clear key will provide that functionality when booted into Windows on an Intel Mac, however. The REC box starts recording a macro; TRK enables track changes mode; and EXT extends the selection -- such that when you click the mouse, your selection is extended to that point.]