Those of us who spend a lot of time online have a slightly different vocabulary than the rest of the world. We use words like blog, webinar, and meme on a daily basis (and actually know what they mean). There is no need to use a standard dictionary because a lot of the definitions we’re looking for simply won’t be there.
http://www.makeuseof.com/tag/showdown-wikipedia-dictionary-wiktionary-urban-dictionary/