are put 'on hold', usually for a minimum period of 30 days after the expiry date, but often for longer. Sometimes names are on hold for months.
This gives the previous name holder a chance to buy the registration back if he/she wishes to do that, and during the hold period you cannot "get in there and grab it". You'll have to wait.
At the end of an on hold period a delete command is issued, and the name registration is deleted all over the world. This process usually takes a couple of days, but can take up to a week.