Memetics
A meme = a replicator of cultural information which one mind transmits
Memetics = the proposed science of how memes are transmitted
From the Wikipedia artices at http://en.wikipedia.org/wiki/Memetics and http://en.wikipedia.org/wiki/Meme
Definition
"The term "meme" was used in 1976 by Richard Dawkins to mean a replicator of cultural information which one mind transmits (verbally or by demonstration) to another mind. Dawkins said, Examples of memes are tunes, ideas, catch-phrases, clothes fashions, ways of making pots or of building arches." (http://en.wikipedia.org/wiki/Meme)
"Memetics is an approach to evolutionary models of information transfer based on the concept of the meme." (http://en.wikipedia.org/wiki/Memetics)
Internalists vs. Externalists
"The memetics movement split almost immediately into those who wanted to stick to Dawkins' definition of a meme as "a unit of information in the brain", and those who wanted to redefine it as observable cultural artefacts and behaviours. These two schools became known as the "internalists" and the "externalists"." (http://en.wikipedia.org/wiki/Memetics)
Key Books to Read
The Electric Meme. Robert Aunger.
The Meme Machine by Susan Blackmore, Oxford University Press, 1999