A meme is an idea or a type of behaviour which spreads from one person to another.
A meme might consist of a trend for grapefruit starters, beards, taking snuff, naming scandals something-gate, or asserting that 42 is the answer to Life the Universe and Everything.
The idea of a meme was dreamed up by Professor Richard Dawkins in 1976 in his book The Selfish Gene. He pointed out that someone's influence can continue down the generations even if his or her physical genes have died out.
Shakespeare and Mozart, for instance (as far as we know) have no descendants alive today, but their ideas live on in millions of us.
Similarly, we don't know so much as the name of the person who invented cooking, but his or her influence has extended for thousands or possibly even a million years.
I've been thinking about memes lately because one was born - or, at least, given a very public impetus - on Sunday 8th May.
You remember Boaty McBoatface? Well, on 8th May a new TV programme hosted by Robert Peston began, and one of its features was a big screen designed to do all sorts of clever interactive...stuff (sorry, I didn't actually watch the programme).
But what to call the screen?
Viewers soon came up with a popular answer: Screeny McScreenface.
And thus is culture born.
Thing To Consider Today: memes. This word is a deliberate echo of the word gene. It comes from the Greek mīmēma, imitated thing, from mīmos, which means mime.