Different users have access to different functions of the site. While anyone can do most things on the site, including reading and editing, administrators can access a few additional functions. See the administrators' how-to guide for a guide on using admin functions. Some functions include: deleting and undeleting pages, page histories, and uploaded files, locking (protecting) a page so it can not be edited or renamed by users without admin rights, blocking IP addresses or user names from editing; and very quick "rollback" of undesirable edits, and editing the interface by changing system messages and skins, among others.