The site notice can be set by admins of a wiki by editing the page MediaWiki:Sitenotice. This shows as a message at the top of all pages, and is useful for notifying the whole community of a wiki of news or a discussion.
Once a contributor has read the notice, they may prefer not to view it any more. If they have cookies enabled, they can dismiss the notice using the "dismiss" link next to the text. This will work whether they are logged in or not. As long as they don't clear the cookie, the notice will remain hidden.
To reset the notice, and make it visible again to all (for example when an admin has put up a new notice) the number in MediaWiki:Sitenotice id needs to be increased by one. If this page doesn't yet exist, it can be created with a starting number of 0. The new notice can be dismissed after reading in the same way as the last.
To clear the message, MediaWiki:Sitenotice should be reset to the default: -
Best practices
- Use a site notice for important or temporary messages updates only. If site notices are used too often, regular users to your wiki might begin to ignore them, which makes it harder to get the really important notices out. When not needed, clear the message as mentioned above.
- Keep site notices short and sweet — one or two lines of text with links to more extensive information is best.
- Keep page load times fast by avoiding images, polls, DPL, or other extensions in the site notice.
- Consider whether to use the MediaWiki:Anonnotice, which allows you to talk only to users that are not logged in, or to show a different message to that group.
- Use the main page, Community Portal, or sidebar for links to news, policies, or help.
- Sitenotice messages should generally not be signed.