Asking and answering - How are You -

How are you? - 

You can add “today,” if you haven’t seen the person for a few days or want to appear especially cheerful. This is a formulaic question, that asks for a formulaic answer, such as “Fine, thanks,” “Pretty good,” “OK” or “All right.”

Fine, thanks. - 

This is a good way to answer the question “How are you?” You can also answer “I’m fine, thanks.” or “I’m fine, thank you.” The latter would be somewhat formal than other two. If you want to return the question, simply add “and you?”

And you? - 

This can easily be tagged on to any response as a way to ask the same question back. “How are you?” “Fine, and you?”

How’s it going? - 

This is a formulaic question, that asks for a formulaic answer, such as “Pretty good,” “OK” or “All right.” It is more familiar than “How are you?” Note the contraction of “how is” to “how’s.” Contractions are very common in the English language.

I’m all right. - 

This is a very casual response to “How are you?” It too, can be followed by “and you?” Note the contraction of “I am” to “I’m.”

OK. - 

This is a casual way to answer “How are you?” or “How’s it going?” You can also say “I’m OK.”

Pretty good. - 

This is a good way to answer the question “How’s it going?”

What’s up? - 

This is a formulaic question, that asks for a formulaic answer, such as “Nothing much.” It is very casual. Note the contraction of “what is” to “what’s.”

Nothing much. - 

This is a very informal response, that can be used to answer “What’s up?” (But not: “How are you?”