In British superstition, a black cat is traditionally considered lucky when it crosses your path.
This belief contrasts with the widespread idea that black cats bring bad luck. In Britain, Ireland, and parts of Japan, a black cat crossing someone’s path can be interpreted positively, while some continental European and North American traditions treat the same event as ominous.
The mixed symbolism has deep historical roots. Cats were associated with witches in parts of early modern Europe, but they were also valued as protectors of food stores and homes. Sailors sometimes regarded cats as lucky shipboard animals, and British folklore preserved several favorable associations.
The belief concerns folklore rather than a measurable effect. Black cats are not biologically different in luck or behavior from other domestic cats, although their dark coats have influenced their place in art, Halloween imagery, and animal-shelter campaigns.