A 'meme' is something that spreads in a mostly unplanned, spontaneous way seemingly from out of nowhere to becoming prominent. Some examples are certain types of genes that remain in a body even though they don't benefit the body that much (this was explained by biologist Richard Dawkins in his book 'The Selfish Gene'), movie and TV catchphrases, internet sayings such as "Desu, and elements of popular culture such as the song "Chocolate Rain" by Tay Zonday. Abstract ideas could also be thought of as memes.
Labeling something as a 'meme' can be controversial. For example, the late biologist Stephen Jay Gould disputed Dawkins' model of meme-based evolution. Many songs commonly thought of as 'memes' have acutally benefited from deliberate outside promotion. Dismissing someone's else idea as "merely a meme" is a common red herring logical fallacy. .
