The KISS principle, or “Keep it simple, stupid,” is a design principle that states that most systems work best if they are kept simple rather than made overly complicated. The phrase was first used by Kelly Johnson, an American engineer who worked on developing the Lockheed U-2 spy plane.

It’s often applied to software development but can also be used in other areas. The basic idea is that keeping things simple makes them easier to understand, use, and maintain.