Error proofing is a concept where systems are designed to help prevent failure. A common Japanese term is poke-yoke. There are different levels of error proofing such as prevention, detection, and warning.
Prevention is where the process is designed to work one way and one way only. An example would be the charger cable for you phone. The end of the cable is shaped so it will only insert into the phone one way.
Detection is a method that senses something is wrong and lets the process know. An example would be a piece of assembly equipment that senses all the components are not in the machine and a light turns on, but the equipment can still cycle.
Warning lets someone know how to correctly execute a process. A colleague of mine showed be a great example of this for our Overhead Projector case.
The group was having a problem with people putting the projector in backwards. It caused damage one time. Quick, simple, and easy to understand. It may not prevent someone from putting the projector in backwards, but it does significantly reduce the chances and makes the right way visual.