Ciao!

Ciao, a photo by king.vulture on Flickr.

The word "ciao" is an informal Italian verbal salutation or greeting, meaning either "hello", "goodbye", "bye" or "hi".

Originally from the Venetian language, says Wikipedia, it was adopted into the Italian language and eventually entered the vocabulary of English and of many other languages around the world.

The word is mostly used as "goodbye" or "bye" in English, but in modern Italian and in other languages it may mean "hello" or "goodbye", similar to the Hawaiian word aloha.