[Xenon]

the userid has an autoincrement function in the db, so for every user it is set up by one, but if you delete a user, the gaps won't be filled.

so if so has the userid 24 it is the 24th user which has registred on your board, but this means not, that 23 users are already registred, because if you have created a test user, and deleted this account, it was a registred member, and so the userid has a gap there now.