The act of forming into a class or classes; a distribution into groups, as classes, orders, families, etc., according to some common relations or attributes.
User Defined Definitions
"the act of distributing things into classes or categories of the same type"
"a group of people or things arranged by class or category"
"the basic cognitive process of arranging into classes or categories"
"restriction imposed by the government on documents or weapons that are available only to certain authorized people"