Padlock: Gold, or brass, depending on your point of view. Commonly called gold as it makes sense that the next level up from semi-protection (silver) would be gold. However, the gold padlock looks like this: — the padlock used for full protection is actually an ordinary (brass) one, and the padlock used for semi-protection is not silver (metal), just silver (color).
Commonly used for: More serious disputes, highly visible pages, such as the main page, or very heavily used templates.
Cascading protection option: If used, also protects all templates and pages transcluded onto a fully protected page.
Commonly used for: Preventing people from persistently recreating deleted articles, or from overriding Common images with local ones. Referred to as salting. Note that the protection is case-insensitive, but the logs (annoyingly) won't show the protection entry unless you enter the exact case which was protected.
Used for: In the MediaWiki namespace, all pages are protected by default and cannot be unprotected. Use of the red padlock has also spread to some other permanently protected non-article pages.
Creation: In the MediaWiki namespace, administrators only.
Editing: Administrators.
Moving: Administrators.
Padlock: Red. The padlock is not actually used on MediaWiki pages since they are used for interface text (see Special:Allmessages), but the red padlock is associated with this type of protection.
These templates can be placed on pages to indicate graphically the level of protection. They do not actually protect pages, which must be done through the protect this page screen or WP:RPP.
