Luck is the phenomenon and belief that defines the experience of notably positive, negative, or improbable events. The naturalistic interpretation is that positive and negative events may happen at any time, both due to random and non-random natural and artificial processes, and that even improbable events can happen by random chance. In this view, the epithet "lucky" or "unlucky" is a descriptive label that refers to an event's positivity, negativity, or improbability.

Supernatural interpretations of luck consider it to be an attribute of a person or object, or the result of a favorable or unfavorable view of a deity upon a person. These interpretations often prescribe how luckiness or unluckiness can be obtained, such as by carrying a lucky charm or offering sacrifices or prayers to a deity. Saying someone is "born lucky" may hold different meanings, depending on the interpretation: it could simply mean that they have been born into a good family or circumstance; or that they habitually experience improbably positive events, due to some inherent property, or due to the lifelong favor of a god or goddess in a monotheistic or polytheisticreligion.