What's a meme?

I have never really put much thought into where the term meme comes from, or what it's really meaning even is.  I suppose I just assumed that the letters stood for something and that the name was given to them by their creator, such as "gif." For me, memes seemed to come out of no where.  They became extremely popular over night and I, along with the rest of the world, quickly learned to use their comedic power.  However, after doing some research, I have found the name goes much further back than their creation, 1976 to be exact.  In his book, The Selfish Gene, Richard Dawson states, "We need a name for the new replicator, a noun that conveys the idea of a unit of cultural transmission, or a unit of imitation. ‘Mimeme’ comes from a suitable Greek root, but I want a monosyllable that sounds a bit like ‘gene’. I hope my classicist friends will forgive me if I abbreviate mimeme to meme. If it is any consolation, it could alternatively be thought of as being related to ‘memory’, or to the French word même. It should be pronounced to rhyme with ‘cream’"(http://www.todayifoundout.com).  To me, this made a great deal of sense.  A meme is an imitation; it is a photo that has been taken from somewhere else and used over and over again with different words and phrases.  The same picture can produce hundreds of memes, and considering that it is a new cultural wave, I feel that Richard Dawson hit the nail on the head.  Here are some I've used recently: