What is a "Meme"

What is a "Meme" the definition in the dictionary is

1. An element of a culture or behavior that may be passed from one individual to another by nongenetic means, esp. imitation.

2. An image, video, etc. that is passed electronically from one Internet user to another

 But on blogs it is a series questions like the "Star Wars Meme" please tell us what it is and who started the "Star Wars Meme" and a link to it.

Please tell us.