Posttraumatic stress disorder (PTSD) is a disorder that may develop after a person is exposed to a traumatic event, such as an assault, rape, car accident, terrorist attack, natural disaster, or military combat. These are the most common situations that lead to PTSD, but any life-threatening situation can lead to the disorder as well. Statistics say that about 8% of adults in the US will experience PTSD during their lifetime, and women are about twice as likely to struggle with it.
So what is PTSD? The disorder usually consists of flashbacks of the traumatic event, avoidance of reminders of the event (such as avoiding conversations about it), detachment or withdrawal from their surroundings, and some somatic complaints. Other symptoms, such as insomnia, hypervigilance (being on alert constantly), and increased fears, can accompany the disorder.
Obviously, this disorder is incredibly distressing to those who experience it. And some research seems to indicate that there is no "cure" for it--that PTSD never really goes away. But the good news is that there are several treatments that have been shown to decrease the symptoms of PTSD and improve the lives of its victims. Cognitive-behavioral therapy (CBT) is one treatment that has been very effective in reducing the symptoms. This form of therapy helps people to manage their fears and anxiety that stem from the traumatic event. Other therapies that are being used to treat PTSD include relaxation therapy, in vivo exposure therapy (which helps people re-experience the event while remaining calm), cognitive restructuring (which helps people restructure their thoughts to be more calm and positive), and psychoeducation (which helps people understand PTSD and its effects).
The best thing that people suffering from PTSD can do is to seek treatment. Even though the most natural response of these people is to try to forget what happened, being able to do that is highly unlikely. Those who try to avoid treatment for the disorder often develop substance abuse problems, sleep problems, and difficulties in their relationships. Seeking treatment through therapy is often very beneficial, and there are many competent professionals who are trained to help victims of traumatic events. The mental health community has created several groups and treatment centers specifically for victims of PTSD, and these include the Disaster Response Network of the APA, the National Center on Disaster Psychology and Terrorism, and the Disaster Mental Health Institute. In particular the National Center for PTSD website had a great deal of information on this disorder. You can find it here.