A Specification (Shortcut: Spec.) is a technical standard. It consists of a set of requirements to be fulfilled by the product or service.

If at least one requirement is not met, the product is "out of spec."

While the above describes how a product/service should be, the term 'specification' is also used to describe, how a product7service really is. This would be more the meaning of a data-sheet.

A list of books about the topic Specification