Cores refer to the central or most important part of something. In various contexts, such as geology, a core can mean the innermost layer of the Earth, which is primarily composed of iron and nickel. In technology, a core often refers to a processing unit within a computer's central processing unit (CPU), responsible for executing instructions and performing calculations. In the context of fruits, a core is the central part that contains seeds, like in apples and pears. This part is typically not eaten, as it is tough and fibrous. Understanding cores helps in various fields, from science to everyday life.