A cloth bracelet will be placed on your wrist at check in. At check out they will snip it off and give you, if you need/desire, a plastic bracelet denoting you are checking out which will allow you to continue to use the facilities until you depart.
You don't want to lose it. There is a charge to replace it. I believe it was $100+ Make sure whoever puts it on has it snug enough. They will loosen up just a bit over the course of the week. We had ours "re-done" in June after we realised the front desk clerk who though very nice was new and made them too loose.
Also as an added note, you will find they dry extremely quickly.
the first time we stayed at the tam we were not too keen on having to wear the bracelets.
we did find that they did dry fast.
i found though having to have it on 24/7 was making me crazy.
mine stretched enough that i was able to squirm my hand out of it and took it off at bedtime.
i do not advise removing your bracelet as i did.
as lisa said, if it gets lost/stolen it cost you $$ to replace it.