The Kids Next Door, or KND for short, is a worldwide organization of trained children under the age of 13 who battle adult tyranny in the animated series Codename: Kids Next Door. The current age of the KND, the seventh age, was founded by Numbuh 0, after he discovered the legendary "Book of KND" that contains all stories of KND operatives' stories for their adventures. The organization's purpose is to protect kids from adult tyranny and teenagers (anyone over the age of 13), but they only battle evil adults, as stated in Operation: M.A.T.A.D.O.R. andOperation: A.M.I.S.H.. All members' codenames are numbers, spelled "Numbuh". It was revealed in Operation: C.A.K.E.D.-F.I.V.E. that in the 19th Century KND, girls were not allowed in the organization.