Microsoft Community Bar adds context-dependent content to the web browsing experience. It is actually an entire platform for applications whose content depends on the page that the user is currently viewing. It is very easy for anyone to create new Community Bar panels.

It is simply a vessel that enables people to snap-in panels that look at the page you’re browsing in IE and return some hopefully useful information to you. The panels are really not much more than framed web pages that serve some specific purpose (tagging a site, enabling comments about a site, rating a site, etc). It is an Internet Explorer add-in that enables users to annotate, notes about and descriptively tag web sites they visit in IE. The bar enables sharing of opinions, tags, and help among all users of the bar and in no way modifies the visited page. The bar is envisioned as a way for people to asynchronously tag and comment on web pages and domains – in essence, to build a community around sites that is distinct from the site itself and enables interaction among people who visit the site from all over the world without having to have to be there at the same time.