What's a tab? Well, it depends where you are.
In America a tab may be an invoice, especially for drinks or food (sadly, not an easy spot for some of us at the moment). In England it might be the badge on the collar of a staff officer:
In Scotland or Northern Ireland, it might be a cigarette (yuk):photo by bachmont
If you're up in the air then it might be found on an aeroplane:
But everywhere a tab is a small flap of fabric or paper or plastic that might be to mark a place in a paper file, as part of a label (perhaps a security label on a food jar, or else a device to stop a battery working in a new electric product) or perhaps a small piece of fabric displaying to the world the size of your dress or the shop from which you bought it.
Today is a day to appreciate such small but useful things.
Spot the Frippet: tab. This word appeared in English in the 1600s, but no one is really sure from where it came. There was an earlier English word tab which meant strap or string, and there's a Norwegian local word tave, which means rag or piece of cloth, and those might be relations of our own word.
The word tab can also be short of tablet.