"Hello" in Russian

I've heard so many different ways of saying hi/hello in Russian! What is the formal and informal way of saying hello.

Is it здравствулте and привет?

:puzzled:

Hello (formal): Здравствуйте (note the spelling)
Hello (informal): Здравствуй or привет

Здорово! (stress on the second syllable)

По телефону- Алло

i've also heard Здрасте!