Over in the United States, we use a variations of greetings everyday. Some of the most common ones are: What's up? How are you? What's going on? How's it going? How's it hanging? What's crackin'? Hello Hi Hey Yo! Being American, I usually hear all of these greetings everyday. I bet there are more common phrases used in other English speaking countries, but these are the ones of which I am most accustomed with.

I would say that "hey" "hi" and "whats up" are the most common. But "Hello" is standard for answering the phone and is also used a lot in more formal greetings in person.

How ya doin? How are you?