A meme is an idea or habit that's passed between people and generations through imitation. An example of a meme is the cultural tradition of women wearing skirts.
A cultural idea, value, habit, or even something like a tune is a meme if it is picked up from someone else. A meme, which is pronounced "meem," will change over time, like younger kids who want to wear the exact same clothes but who eventually develop their own, though similar, styles. Recently, meme has become commonly used to refer to Internet memes — pictures, videos, or even slang words that are shared between Internet users.