Formal:
* Au revoir: This is the most common and formal way to say goodbye. It literally means "until we see each other again".
* Bonne journée: This means "have a good day" and is appropriate for daytime farewells.
* Bonne soirée: This means "have a good evening" and is used for evening farewells.
Informal:
* Salut: This is a casual way to say goodbye, similar to "bye" in English.
* Ciao: This is a more informal way to say goodbye, borrowed from Italian.
* À plus tard: This means "see you later" and is a good choice for friends and family.
* À bientôt: This means "see you soon" and is a more affectionate way to say goodbye.
* Bisous: This means "kisses" and is a very informal way to say goodbye to someone you know well.
Other options:
* Bonne chance: This means "good luck" and is used when someone is leaving to do something challenging.
* Prenez soin de vous: This means "take care of yourself" and is a thoughtful way to say goodbye.
It's also important to consider the context of the goodbye. For example, if you are leaving work, you might say "bonne journée" to your colleagues. If you are leaving a party, you might say "à plus tard" to your friends.
Remember, the best way to say goodbye in French is the way that feels most natural to you!