However, you can also use more formal or informal variations depending on the context:
Formal:
* Thank you very much.
* Many thanks.
* Thank you so much.
* I am very grateful.
Informal:
* Cheers.
* Ta. (This is a very informal and abbreviated version of "thanks.")
* Thanks a lot.
* Thanks.
Other expressions of gratitude:
* I appreciate it.
* You're a star.
* That's really kind of you.
* I owe you one.
The best way to choose the appropriate phrase is to consider your relationship with the person you are thanking and the situation.