K.I.S.S.

Acronym for "Keep It Simple, Stupid!". A web design principle. This means don't use blinking text, scrolling marquees, background music, and the like just because you can. Don't use a font that drips blood, or a bunch of cheesey animated gifs. Just make it look nice, and simple, like you were designing a room in your house.

Not just a web design principle. It is also an ancient engineering maxim. The reasoning (proven through long and bitter experience) is that, the more parts a system has, the more things there are that can go wrong, and the harder it will be to fix. This applies to physical machines, software programs, and any other type of system than an engineer might create.