CheckUser is an extension that allows for the checking of IP addresses used by a given username, and which usernames are used by a given IP. In the vast majority of cases, CheckUser rights are only given to Wikia Staff and the Volunteer Spam Task Force (VSTF), but any admin of any wiki can request a check from staff when necessary.
What is CheckUser?
CheckUser is an extension used mostly by Wikia Staff, but also by the VSTF, in order to check whether an IP has been used by a given username or what IPs a given user has edited with (logged in or otherwise). The length in which IP data is stored varies, but sometimes CheckUser results can go as far back as one year.
CheckUser is often used to determine whether someone is using multiple accounts for vandalism or spamming, if an IP address that spammed or vandalized has accounts attached to it, or if a vandal or spam account is using any other IPs that need to be blocked. The use of CheckUser for these purposes is generally done by the VSTF.
How can I request a CheckUser?
To request a CheckUser search, you need to be the administrator of a wiki or have the verifiable permission of the administrator to request the CheckUser search. If those conditions are met, you can contact the Community Support Team and they will run the CheckUser search for you. Please provide as much information as possible while doing so, such as the reason for why you want the team to check the accounts/IP addresses, what the account names/IP addresses are, and any other information you feel is relevant.
CheckUser should not be used lightly, and a search should only be requested in cases that involve highly disruptive users. Requests should not be made out of curiosity as to whether one person is using multiple accounts, but instead should be requested if there is a suspicion of sockpuppetry and if that sockpuppetry is disrupting the wiki. A case of one user with multiple accounts may violate local policies, but if they are not disrupting the wiki then it is better to ignore them and let them be.
Please note that results for matching accounts only appear if they use the same IP. Someone may be using two accounts, but if they are using different IPs then there is no way to definitively connect the two accounts with a CheckUser search.
Who has CheckUser rights?
Wikia Staff members have global CheckUser rights, meaning they can run a check on any wiki when requested. The VSTF also has global CheckUser rights for helping in cleaning up spam and vandalism. Some Helpers also have CheckUser rights.
In a limited number of cases, some local wiki administrators also have been given CheckUser rights. These rights only apply on their wiki, and CheckUser rights are given to administrators only in cases of very extreme and excessive vandalism. In general, requests for CheckUser rights will be declined.