Xie xie
The most common way to say “thank you” is xièxie (谢谢).
You can also say xièxie nǐ (谢谢你), which adds on the pronoun nǐ (你), meaning “you.”
The formal version is xièxie nín (谢谢您).
Another phrase is duōxiè (多谢), which is like saying “Thanks a lot,” since duō (多) means “a lot.”