Links are the glue of the blogosphere.

First, links make up a weblog's blogroll: the list of links (generally on the side of a blogger's page) that show which blogs they read regularly. These blogrolls are the key to tying together individual blogs into a community.

Links also provide a convenient way for bloggers to link to content outside of the blogging universe: cool sites, interesting articles, and the like. And on the flip side, those same links provide a convenient way for blog indices like Blogdex and Daypop to keep score of what's hot or not.