Can someone explain to me how air tags work

[PokerFace2023]

I was on my iPhone earlier on the train and a picture of an air tag kept coming up and asking me if I wanted to connect to the air tag.
I don't have an air tag so someone close by on the train must have, but I didn't think my phone would be able to connect to someone else's.

That should only happen if the AirTag isn’t already registered to an account. I lent a couple of mine to a friend and when he returned them (disconnected) I had to take them out of my pocket as my phone kept trying to connect to them.

@DontCallMeBaby so if someone had just bought one?

It’s a while since I got mine but I’m almost certain they have one of those little plastic tags when they’re first bought, the kind you have to remove to activate the battery. So you wouldn’t get a brand new one trying to connect, no.