KISS principle

The KISS principle is "Keep It Simple, Stupid". It is an acronym, with the letters KISS making the beginnings of the important words. It was used as a principle for design by the U.S. Navy in 1960. The phrase is said to have been first used by Kelly Johnson, lead engineer at the Lockheed Skunk Works.
There are several variations of the phrase, such as "Keep it short and simple".