Help:Block user

Administrators can use the block user page to block IP addresses and user accounts. This should only be done to combat vandalism or abuse of the wiki.

If you are an administrator and you need to block someone, go to Special:Blockip. You will be presented with a form to complete containing the following fields:

IP Address or username - specify the IP address or the username of the user you want to block. You can specify an IP range using CIDR format. Make sure you read the Help page on IP ranges before attempting to block a range.
Expiry - specify the duration of the block. This can be anything from 2 hours to infinite. An infinite block lasts forever.
Reason - specify the reason for the block.
Other/additional reason - add any further information about the reason for the block

There are three options which determine how the block will be applied:

Block anonymous users only - for IP address or range blocks, selecting this option will limit the block to anonymous users editing from that address. Logged in users will still be able to edit from the affected IP address(es). This option has no effect if you are blocking a username.
Prevent account creation - for IP address or range blocks, this option stops anyone using the affected IP address(es) creating a new user account. If you are blocking a username and you turn on autoblocking (see the next option), this option will prevent autoblocked IP addresses from creating accounts. If you are blocking a username and you turn autoblocking off, this option has no effect.
Autoblock any IP addresses used - this turns on autoblocking. It will block the IP address most recently used by this user when editing a page for 24 hours or the duration of the block (whichever is the shorter). If they attempt to edit a page from another IP address whilst their account is blocked, that IP address will also be blocked for 24 hours or the outstanding duration of this block (whichever is the shorter).
Hide username/IP from the block log, active block list and user list - stops the username/IP address appearing in the block log, active block list and user list.
Prevent user from sending e-mail - stops the user from using the wiki to send email to other users. This option has no effect if you are blocking an IP address.

Unblocking

When viewing the list of currently blocked IP addresses and usernames, administrators see an "unblock" link for each entry. Clicking on this link takes you to a confirmation page where you can confirm that you want to unblock the user/IP address. Note that it is not possible to unblock individual IP addresses within a blocked range.