What is the difference between these two sentences: ‘How are you?’ and ‘How do you do?’
How do you do? is very formal and is not used very much, especially by younger people, these days. It may be used on first meeting and accompanied by a formal handshake when both partners issue the same greeting. The reply to How do you do? is How do you do? Then it would be a matter of getting straight down to the business in hand, e.g. ‘I see that your company has been performing very well in South East Asia...'
The more usual exchange between two people meeting with a handshake on a fairly formal basis for the first time would be: Pleased to meet you. Or: Nice to meet you.
The most common way of greeting someone both at an informal level and more formally would be: Hello! How are you? to which the standard reply is: Very well, thank you. or: Fine, thank you. (Note that the question is not usually meant or interpreted as a searching enquiry after the person’s health.) After we have given this reply, we often repeat: (And) how are you? or: (And) what about you? The response is still the same: Fine, thanks.
At the most informal level, among friends and particularly among young people, the most common greeting would probably be: Hi! to which the response is: Hi! This might then be followed by one of the following: How are things?, How’s things?, How’s it going?, (Are) you OK? to which the answer is probably: Yeah, fine! or with typical British understatement: Yeah, not so bad!
At a formal level, and again accompanied by a handshake, the most common farewell would probably be: (It was) nice to meet you or Nice to have met you. If a follow-up meeting has been arranged, this might be accompanied by: I’ll see you in three weeks. Bye, now.
At a more informal level too, on first meeting, it would be quite normal to say: Nice to have met you. Bye/Goodbye.
Among friends, farewell might be taken (by a combination of) some of the following:
* 'See you.'
* 'See you later./tomorrow./on Saturday./etc'
* 'Take care.