What is the origin of the idiom "be in luck" and when to use it?

The origin of the idiom "be in luck" is believed to be from the Middle English word "luc", meaning "chance" or "fortune". This word is derived from the Old French word "luc", which also means "chance" or "fortune". The idiom "in luck" is used to describe someone who is fortunate or lucky. The phrase "in luck" is often used in informal conversation to describe a situation where someone is experiencing good fortune or luck.