Memes are anything you want them to be. They range from simple pictures and text critisizing certain things and actions. To reoccurring text that is either famous or infamous. An example of this is the famous Fresh Prince story. Which would start as an interesting story, usually relevant to the thread it is being posted in, and then finish with "I whistled for a cab and when it came near The license plate said fresh and it had dice in the mirror If anything I can say is that this cab was rare But I thought 'Man forget it' - 'Yo home to Bel Air".
Meme originated because of Richard Dawkins word play on the word gene. A meme is something that is distinct in a certain culture. Internet memes are most popular and have thousands of variations all over the internet. It is apparent that the internet has the most diverse culture and customs.