Where did this phrase come from?

[Buster Brown]

Why do people say, "How do you do," when meeting a new person?  It just doesn't make sense.  Does anyone know where this phrase originated?  Thanks.

[Quizmonster]

It was originally just 'How do you?' and used as a greeting as far back as the 1400s. In this sense, 'how do you' just means 'in what condition or state are you?' You find the exact same sense in more modern phrases such as 'How are you doing?'...'I'm doing fine' and so on. There is no further question such as 'How am I doing what?' or 'What are you doing fine?'

[GrumpyOldMan]

Godd one from Quizmonster.  The Scots put it more simply - "How you doing?"

[doghandler]

Some Scots (Aberdeen area) say;

Fet Like!

(translated to "What like").