KISS, an acronym for "Keep it simple, stupid!", is a design principle first noted by the U.S. Navy in 1960.[1][2] First seen partly in American English by at least 1938, KISS implies that simplicity should be a design goal. The phrase has been associated with aircraft engineer Kelly Johnson.[3] The term "KISS principle" was in popular use by 1970.[4] Variations on the phrase (usually as some euphe