Formal:
* さようなら (Sayōnara): This is the most formal way to say goodbye and is used in situations where you're leaving someone you don't know well or someone older than you.
* 失礼します (Shitsurei shimasu): This literally means "excuse me," but it's used as a polite way to excuse yourself from a situation.
* お先に失礼します (Osaki ni shitsurei shimasu): This is a more formal way of saying "excuse me" and implies that you're leaving before the other person.
Informal:
* じゃあね (Jāne): This is a casual way to say goodbye to friends or family.
* またね (Matane): This means "see you later" and is another casual way to say goodbye.
* バイバイ (Bai bai): This is a direct transliteration of the English "bye bye" and is often used by young people.
Other options:
* 行ってきます (Itte kimasu): This is used when you are leaving your home. Literally, it means "I'm going and will come back."
* 行ってらっしゃい (Itte rasshai): This is used when someone is leaving home. It means "Go and come back safely."
The best way to choose the right word depends on the context and your relationship with the person you're talking to.