A meme is "an idea, behavior, or style that spreads from person to person within a culture."
A meme acts as a unit for carrying cultural ideas, symbols, or practices that can be transmitted from one mind to another through writing, language, gestures, rituals, or other imitable phenomena.
The term was coined by Richard Dawkins in his book 'The Selfish Gene"published in 1976. A meme is considered a unit of human cultural evolution analogous to genes.
It is now most commonly associated with a style of internet image (macro image) and overlaid text.