1- "Salve" is more formal than the simple "ciao". So, one uses the second one with friends, parents, relatives and all the people he knows somewhat well. "Salve" is used with all other people. 2- You can use either one or the other, they're synonyms: notice that you'll use it only the first time you happen to meet a person, once you know them you won't use this expression anymore when you'll meet them again. 3- Since we're basically speaking of written Italian, it's a good custom to capitalize the letter L. 4- Even "ArrivederLa" is really formal, and I advise you to use it only in written Italian when a you're required to be very formal at all. In spoken and less formal written Italian you should use the simpler "Arrivederci". 5- As anticipated above, "ciao" is the most informal out of the three, so you can use it with people you know very well; "arrivederci" is quite formal and you should use it with people you don't know very well or you don't know at all; "addio" is used when you think you'll never see a person again, because of death, departure and so forth. I hope this helps! Ask if you haven't understood something

Ciao! 1) "Salve" is a little bit more formal than "Ciao", but I'd recommend to use "Buongiorno" or "Buonasera" if you want to be formal! 2) Yes, you can use either "Tanto piacere" or "Molto piacere" (or even just "Piacere) 3) If you want to be extremely formal, yes :) 4) It's the formal version of Arrivederci 5) Arrivederci is more formal than Ciao. Addio is more like "Farewell", but nobody uses it!

1. Salve - hello ; ciao - hi and bye 2. Yes, you can say: tanto piacere, molto piacere or simply piacere 3. Lei - you (formal) , lei - she 4. ArrivederLa - formal way for good bye 5. Ciao is very informal. Use it only with your friends. Addio and Arrivederci are more formal greetings.