Post traumatic stress disorder is developed when a person experiences or witnesses a traumatic event, such as front-line combat, an earthquake, or sexual assault. To qualify for post traumatic stress disorder, the event must be physically dangerous or life-threatening, either to one self or somebody else. I know a little bit about this disorder because my grandpa was in the Vietnam war. After speaking with him about it, I can sense that it is a touchy subject. He could be a victim of it, because he explains the flashbacks he has of the traumatic event. He was there from 1965-1970, and from what I got from it is that five years of war can be very traumatizing. I asked if he killed anybody, and he responded, "with five years of combat I would expect you to know the answer to that question." In the book, it says that post traumatic stress disorder involves a constellation of symptoms that can be quite debilitating. He doesn't show many symptoms compared to the people that have the disorder in the worst way, but he says he still thinks about it from time to time. My grandpa is a very outgoing happy man, but I feel I can sometimes see a side of him that is not normal in a person that has not been through what he has. This is why people should be wary while speaking with a person that has gone through something traumatic.