Memes appear to be a type of autopoietic system. They circulate and reproduce themselves, using people and mass media as hosts. Memes pass from consciousness to consciousness as a viruses pass from host to host, and no one really given them much thought before parotting them. They are not the product of human thought. This is what Wikipedia (You have to start somewhere!) says about memes:
A meme (/ˈmiːm/ MEEM) 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, speech, gestures, rituals, or other imitable phenomena with a mimicked theme. Supporters of the concept regard memes as cultural analogues to genes in that they self-replicate, mutate, and respond to selective pressures.
Proponents theorize that memes are a viral phenomenon that may evolve by natural selection in a manner analogous to that of biological evolution. Memes do this through the processes of variation, mutation, competition, and inheritance, each of which influences a meme’s reproductive success. Memes spread through the behavior that they generate in their hosts. Memes that propagate less prolifically may become extinct, while others may survive, spread, and (for better or for worse) mutate. Memes that replicate most effectively enjoy more success, and some may replicate effectively even when they prove to be detrimental to the welfare of their hosts.
Contrary to some claims, memes do not reside in the brain; they circulate through a communication system. There is no point in searching brain scans for memes. Sociologists and system theorists are better equipped than neuroscientists to understand memes.
The rise of certain political figures and social movements can be explained in large part through a theory of memes. Memes that are simple, easily remembered, easily spread and, possibly, capture some kind of social tension tend to succeed–thus the power of the slogan and soundbite.