What do "tabs" look like?

Question

This is the definition of flag on Dictionary.com:

Flag n.

5.to mark (a page in a book, file card, etc.) for attention, as by attaching protruding tabs.

I have an idea of what a tab is, but what exactly does it look like?

Answer 1

One common kind of protruding tab...

When I had an accountant filling in my tax returns (which ran to many pages), he used to attach tabs like that on certain pages - red where I needed to sign something, and green for sections I was supposed to read and double-check (which I rarely did! :)