A meme is a dominant social theme with the strength for propagation from one generation to another.
A dominant social theme is a belief system (usually concerning a purported social or natural problem) promoted by the monetary or power elite. The related problem, as it is presented, may be centered on people themselves (e.g., overpopulation) or be caused by people (e.g., global warming).
A dominant social theme typically is launched from one or more centers of the elite's global architecture, such as the United Nations, World Bank, World Trade Organization or World Health Organization. The theme is then rebroadcast by the mainstream media. Dominant social themes are notable for their resistance to contrary evidence, and they invariably imply a need for unaccountable, elite authorities to impose a solution.
With sufficient repetition in the mass media (including "news" and entertainment presentations) and through enshrinement in school curricula, a dominant social theme can become so engrained in the public mind that it is passed from one generation to the next, as though it were folk wisdom. It becomes virtually exempt from questioning.
The fear of overpopulation is a meme, as the worry now has spanned generations. A generalized fear that the world may run out of resources, including basic resources such as oil and water, appears on its way to becoming a meme.
According to various sources, The British scientist Richard Dawkins presented the term in his book, The Selfish Gene (1976). It was his idea that a meme encapsulated the spread of ideas and could evolve in some sense as could a gene. The term has become very popular over the decades, especially since the advent of the Internet which could be seen, in some sense, as validating the concept.