KISS原则是英语 Keep It Simple, Stupid 的首字母缩略字。KISS原则是指在设计当中应当注重简约的原则。同时这原则亦有应用在商业书信、设计电脑软件、动画、工程上。原文当中有很多其他版本，包括："Keep It Simple & Stupid"（在西欧文学中最常使用）、"Keep It Sweet & Simple"、"Keep It Short & Simple"、"Keep it Simple, Sweetheart" 及 "Keep it Simple, Sherlock"。

KISS is an acronym for "Keep it simple, stupid" as a design principle noted by the U.S. Navy in 1960. The KISS principle states that most systems work best if they are kept simple rather than made complicated; therefore simplicity should be a key goal in design and unnecessary complexity should be avoided. The phrase has been associated with aircraft engineer Kelly Johnson (1910–1990). The term "KISS principle" was in popular use by 1970. Variations on the phrase include "Keep it Simple, Silly", "keep it short and simple", "keep it simple and straightforward" and "keep it small and simple".