A fully-protected page cannot be edited or moved by anybody, unless they are an administrator, interface-admin, or staff member. The main page is an example of it. A cascade protected page and its items mean that it will always be fully protected.
A semi-protected page cannot be edited by users who are either not signed in or have an account but are not yet autoconfirmed (made at least 10 edits and had an account for at least 1/2 a week). Over 2,100,000 users are autoconfirmed, so only 26.25% of users cannot edit these pages.
A Template-editor protected page can only be edited by template editors/admins, exclusive to templates.
An example of a lock:
A Move-protected page can only be moved (changing the page name) by administrators.
An Upload protected page only allows you to overwrite the file if you are an admin.
An extended confirmed page cannot be edited by non-admins, unless they had an account for 1 month and have made 1/2K edits.
An interface protected page can only be edited by interface administrators; it is always permanent.
Admins can also prevent creating a page.
Some pages are protected by the office too.