A protected page is one which can only be edited by sysops. There are a number of possible reasons why a page might be protected. 1) Permanently * Pages in the MediaWiki namespace are protected by default, for several reasons: 1. * Many messages are in plain HTML, hence users could insert malicious scripts, 2. * Vandalism of some messages would be extremely disruptive; for example changes to the text of the links in the sidebar would immediately be visible to all users, 3. * A few messages can cause the software to stop working if changed. (For this reason admins should only change the MediaWiki namespace if absolutely certain of what they are doing.)