Most wikis can be edited by anyone and everyone. Some wikis are even available to people without an account, so sometimes wikis will become a target for vandals to add unwelcome, disruptive or even misleading content. There are many ways to prevent this. Individual pages can be protected to allow only certain users, or only those with an account, to edit them. Administrators can also block users who make repeated vandalous edits after a minimum of a single warning. Vandalism may not be stopped totally, but regular, careful checking can limit the amount of disruptive edits you will see in a day.