Actually I don't understand it completely myself. I don't really know the science behind it. But what I do know is that it takes memories and "reprocesses" them again, but this time through causing less trauma to the individual.

EMDR can be thought of as a physiologically based therapy that helps a person see disturbing material in a new and less distressing way.

Like someone used the memory of them having an allergic reaction as a traumatic experience. You would go through that memory again and then maybe make a different outcome or be in a safer space or have safer people with you.