Formal:
* Na shledanou: (nah shleh-dah-nou) This is the most common and polite way to say goodbye in formal situations. It literally means "until we see each other again."
* Sbohem: (sbo-hem) This is a more formal and slightly more distant goodbye, meaning "goodbye" or "farewell."
Informal:
* Ahoj: (ah-hoy) This is the most common and casual way to say goodbye. It can be used with friends and family.
* Čau: (chow) This is another informal goodbye, similar to "ciao" in English.
* Měj se hezky: (may-seh hehz-kee) This means "have a nice day" or "take care."
* Na viděnou: (nah vi-dyeh-nou) This is a slightly more formal way to say goodbye than "Ahoj," but still informal enough for friends and family.
Note: When using "Na shledanou" or "Na viděnou", you can also add a phrase like "v práci" (at work) or "doma" (at home) to specify when you'll see the person again. For example:
* Na shledanou v práci: (See you at work)
* Na viděnou doma: (See you at home)
Remember that Czechs tend to be more formal in their interactions, so it's always better to err on the side of formality when you're unsure.