It stands for Eye Movement Desensitization and Reprocessing. The therapist moves her finger back and forth in front of your eyes and you follow the finger with your eyes, which mimics REM sleep. Then you talk about your past trauma and it's supposed to help your reprocess your trauma. We have PTSD because we were never able to fully process the trauma and this is supposed to accomplish that. My T says experts still don't know completely why it works, but it does show to reduce trauma.