every user is identified by the chronological number of his registration.
so, for instance, RCK is u=1 and mine is u=1269. you can check yours by clicking on your nickname in a thread.
if you check in the main page of the board you can see the last person who has registered.
currently the last person is u=9878
but why then we have, read it a line above that, only 2204 members of whych active are only 898? what those discrepancies means? do we have had actually more tha 7000 bans???