Although PTSD is usually associated with soldiers returning from war, it covers a significantly wider population. PTSD is a pervasive mental illness that occurs due to the experience (or witness) of trauma associated with death, the threat of death, serious injury, sexual violence, etc. Traumatic events are typically unexpected, and the individual can often feel powerless to stop or change the event. Traumatic experiences can be suppressed as the body will attempt to "erase" the memory, resulting in it showing up in other ways.