Ciao is a common informal way to say “goodbye” – or, rather, “Bye” – in French.
You might be wondering why this Italian word is on our list of French vocabulary, but Ciao has actually been borrowed into a number of other languages, including French.
It’s surprisingly difficult to find out when exactly Ciao began to be used in everyday French. According to this article from Le Figaro, it was in the 1950’s. Regardless of when it started, Ciao continues to be used quite often in informal, everyday French.
Unlike its original Italian meaning, Ciao is only used to mean “goodbye” in French, not “Hello” as well.
You may hear some French people end a phone call with Ciao ciao. Sort of like “Bye bye” in English, this could be said in a neutral, flippant, or joking tone.