Formal:
* Muchas gracias: This is the most common and versatile phrase. It's appropriate for most situations, especially when speaking to someone you don't know well or someone older than you.
* Muchas gracias por todo: This means "Thank you very much for everything." It's a good option if you want to express your gratitude for multiple things.
Informal:
* Muchas gracias: This is also used in informal situations, but it can be shortened to just "Gracias."
* Muchas gracias de verdad: This means "Thank you very much, really." It adds a bit more emphasis to your gratitude.
Other options:
* Gracias por todo: This means "Thank you for everything." It's a good alternative to "Muchas gracias por todo" if you want a shorter phrase.
* Te agradezco mucho: This is a more formal way to say "Thank you very much." It's appropriate for situations where you want to express your sincere gratitude.
Note: The most common and generally appropriate phrase for most situations is "Muchas gracias." You can't go wrong with it!