Meme: pron. meem (noun) a cultural unit, an idea or value or pattern of behavior, that is passed from one person to another by non-genetic means (as by imitation); “memes are the cultural counterpart of genes”
wordnetweb.princeton.edu/perl/webwn

Alright ad guys. Here it is, the reason that the Internet is made of cats. Memes are the germs of the Internet. You need these germs to make a healthy community. Social networking sites are built on sharing these cultural units. A meme is all about sharing, creating, and improving. Sites like “Today’s Big Thing” and “Know your Meme” are built on propagating and disseminating these cultural germs. It didn’t start with the internet though. Ever heard of Friends? They created a global phenomenon with “How you do’n?” That’s a meme. If you are in the ad business, it is important to know about and study the inception of current memes. People are successfully and often inadvertently doing what we are paid to do. They are creating culture, causing chatter, and affecting behavior.