Coined by popular science writer Richard Dawkins in 1996, a "meme" is any idea that spreads among social groups. It was coined as a variant on "gene." As genes in nature struggle to outcompete rival gene-sets, memes in social environments compete with other memes for our attention. The "meme" view of cultural evolution sees the totality of human ideas as an ecology of self-propagating, mutating, evolving entities. The rising protoscience concerning memes is called "memetics."
Without experiencing changes as they pass from mind to mind, memes could not evolve. By analogy to biological evolution, these changes are called "mutations," although the underlying dynamics of genetic and memetic mutation are radically dissimilar. Even though the workings of genes and memes can be very different, they share certain similarities.
One thing genes and memes have in common is differential self-replication. Certain genes and memes reproduce more effectively than others, meaning they become more numerous than rival variants. These variants become the context within which the next round of mutant variants will compete.
Although neither genes nor memes are independently self-aware, they "selfishly" create behaviors or structures optimized for their own continued survival and prosperity, not necessarily that of the host. In memetics, cults are often used as an example of this. Obviously, memes and genes may contribute to the continued survival and prosperity of the host, but only insofar as it helps their own replication. Genes and memes also operate in parasitic and symbiotic arrangements. In the same way that gene-complexes, or organisms, exploit or help each other based on their specific niche, meme-complexes — worldviews — develop similar strategies as it suits their ability to propagate.
Physically, memes are most often defined as neurological patterns within human brains, although art, culture, science, and other artificial structures are often regarded as carriers of memes or representations of memes in the external world. Though memetics is sometimes criticized as a renamed incarnation of sociology or group psychology, the field possesses its own journals, researchers, and techniques that set it apart from historical disciplines. The term "meme" has become an infectious meme itself, appearing in many popular magazines and books on marketing, business, and psychology.