As explained by another blogger:
In science, a Meme (pronounced to rhyme with “theme”) is a self-propagating unit of thought that is spread from one host to another. Richard Dawkins invented the term as a kind of idea-gene. Like genes, as Memes spread they mutate or die. Only the fittest Memes survive.
For bloggers Memes have become synonymous with internet quizzes, surveys, and novelties that people link to and pass around on their blogs, forums and via email, things like the “which superhero are you most like” test…Fun or just interesting, it is only those that capture your imagination that you will take part in and propagate, apart from those you do out of a sense of duty to your friend who started it. The latter don’t tend to get very far.
Memes are interesting content when done right, and can give you an insight into others personalities and histories that you wouldn’t ordinarily have access to. But it’s mostly about links. The initiator gets a ton of links (all participants link back to the person who started the Meme) and everyone else gets some amount of link love too. You link to the next in the chain (”tag” them) and they link back when they complete what they have to do to participate.
I know you wanted to know but were afraid to ask...