A notice is a posted message from an editor to other editors and users who are viewing a page.

Notices may warn of errors, such as a lack of neutrality on a page that seeks it, failure to follow a particular format, or some other caveat that readers should note and editors must respect.

For examples and a list of notices that can be used see notices.

See also how to wiki well, wiki best practices, editor guidelines, terms of use and wiki etiquette.