A conventional greeting used mostly after being introduced to someone, as in And this is our youngest—say “How do you do” to Mr. Smith. Although it is a question, it requires no reply. Originally, in the 1600s, this expression was an inquiry after a person's health or standing, how do you do meaning “how do you fare?” Today we usually express this as
How are you? or
How are you doing? or
How goes it? or
How's it going? Even more general are the slangy locutions
How are things? or
How's tricks? All of these greetings date from the first half of the 1900s.