不客气。
When to use
This is the standard and polite response when someone thanks you for something. It's equivalent to 'You're welcome' or 'No problem.'
How it works
Literally, '不客气' (bú kèqi) means 'don't be polite' or 'don't stand on ceremony.' It implies that the favor was not a burden and no special politeness is required.
- 不客气 (bú kèqi): You're welcome (polite response to thanks)
Pronunciation Note
The character '不' (bù) is fourth tone, but when followed by another fourth-tone syllable ('客' - kè), it changes to second tone ('bú') according to tone sandhi rules. This makes the phrase sound like 'bú kè qi'.
Notes
Standard reply to 'thank you'.