后悔是人类的一种心理。后悔通常会在完成某些事或做了某决择之后认为错了之后，企图去改掉却没有办法去改的时候，而产生的心理。

后悔产生的情况很多，视乎该人是否认为自己错了、做错后后果的严重性和该人自己有否懊悔等。

Regret is a negative conscious and emotional reaction to personal past acts and behaviors. Regret is often expressed by the term "sorry" whereas "I'm sorry" can express both regret and sympathy. Regret is often a feeling of sadness, shame, embarrassment, depression, annoyance, or guilt, after one acts in a manner and later wishes not to have done so. Regret is distinct from guilt, which is a deeply emotional form of regret — one which may be difficult to comprehend in an objective or conceptual way. In this regard, the concept of regret is subordinate to guilt in terms of its emotional intensity. By comparison, shame typically refers to the social (rather than personal) aspect of guilt or (in minor context) regret as imposed by the society or culture (enforcement of ethics, morality), which has substantial bearing in matters of (personal and social) honor.