The Harlem shake can be two things:
First, its an Internet meme (an idea or concept that spreads on social media). Basically the meme is a short video of a group of people gathering to perform a comedy sketch with an excerpt from the song "Harlem Shake."
The dance, based on Ethiopian dance Eskista, got its start in 1981 by a Harlem resident"Al B". It gained ground in 2001 when G. Dep featured the Harlem shake in his music video "Let's Get It." It's perfect for dancers who don't like to move their feet — it has mostly shoulder and arm movements.
Note, the dance being done in the Internet meme is not the Harlem shake. Got that?
We've posted a how-to video and one on the origins of the dance and its cousins. Get those shoulders shaking.