Wikipedia:Software notices

There are a number of software notices to display message(s) to broad sets of Wikipedians.

CentralNotice
Shows to all users on all projects (or all users in a specific language, depending). Controlled at meta:Special:CentralNotice. See also CentralNotice.

Sitenotice
Shows to all users; appears above the page title. Dismissable and shows only to users with JavaScript support. Controlled by MediaWiki:Sitenotice and MediaWiki:Sitenotice id.

Anonnotice
Shows to all anonymous users; if blank, the sitenotice shows to anons as well. Appears above the page title. Controlled by MediaWiki:Anonnotice. Not dismissable.

Watchlist notice
Shows to all users who use a watchlist. Appears above the horizontal rule on the watchlist. Controlled by MediaWiki:Watchlist-messages. Dismissable using JavaScript found in MediaWiki:Gadget-watchlist-notice.js (can be enabled or disabled through the Gadgets section of your Preferences).

Geonotice
A watchlist notice that only displays to users in a certain geographical area, although geolocation is not perfect. Added and controlled by MediaWiki:Gadget-geonotice.js. See Geonotice. Dismissable by JavaScript.

Editnotices
Shows to all users who are able to edit the page. Appears above the edit textarea. More information available at Editnotices.