The placement of an incident into a hierarchy of descriptors that indicate what the incident is generally about. For example, an incident could be classified as being related to software, and then to Microsoft, and then to Word 2003.
— Computer ScienceA systematic organization of classes.
— Computer ScienceThe determination that official information requires, in the interests of national security, a specific degree of protection against unauthorized disclosure, coupled with a designation signifying that such a determination has been made.
— USA Army