Poka-Yoke is Japanese for mistake-proofing. "Poka" means inadvertent mistake and "yoke" means prevent. It is any mechanism that either prevents a mistake or makes the mistake obvious so that it is corrected immediately. Shigeo Shingo, a Toyota Industrial Engineer, is credited with it's inception.

A good example of a poka yoke can be demonstrated by inserting a floppy disk into your computer, upside down. You will note that it can only go in half way. That is due to a tab inside the slide that is pushed aside by the beveled corner of the floppy disk. The squared corner jams against the tab, stopping the error from happening.