With our rat trap there are four trap states: open not set, open set, shut triggered with catch, and shut triggered no catch.

If the trap state is triggered with catch, opening it gets rid of the trap state for the caught rat.

Trap states are energetic states in a semiconductor's bandgap that can be caused by a number of factors, including: Material impurities, Grain boundaries, Interfaces between layers of different materials, and Natural material disorder