From Mises Wiki, the global repository of classical-liberal thought
A meme is an idea or piece of information that spreads by means of meme replicators such as humans. Religion is a common meme, as are chain letters and computer viruses. A meme can have certain aspects that make it more likely to spread, such as a promise or threat of certain consequences depending on whether action is taken to replicate it. For example, political philosophies are often pitched with dire warnings that unless one supports a cause and gets one's fellow voters to support it, economic catastrophe for one's societal group (e.g. the middle class) will ensue. The demarcation between memes and genes is somewhat arbitrary, but usually the distinction is that a gene is replicated through biological reproduction in which the gene-carrier produces offspring with the same genes, while transmission of a meme occurs by means other than biological reproduction.