The definition of posttraumatic stress disorder is persistent states of anxiety as a result of profound mental and extremely stressful experience.
PTSD is an emotional illness that is usually developed as a result of a terribly frightening, life-threatening, or otherwise highly unsafe experience. PTSD sufferers re-experience the traumatic event or events in some way, tend to avoid places, people, or other things that remind them of the event (avoidance), and are exquisitely sensitive to normal life experiences (hyperarousal). Although this condition has likely existed since human beings have endured trauma, PTSD has only been recognized as a formal diagnosis since 1980. However, it was called by different names as early as the American Civil War, when combat veterans were referred to as suffering from "soldier's heart." In World War I, symptoms that were generally consistent with this syndrome were referred to as "combat fatigue." Soldiers who developed such symptoms in World War II were said to be suffering from "gross stressreaction," and many troops in Vietnam who had symptoms of what is now called PTSD were assessed as having "post-Vietnam syndrome." PTSD has also been called "battle fatigue" and "shell shock'"
Complex posttraumatic stress disorder (C-PTSD) usually results from prolonged exposure to a traumatic event or series thereof and is characterized by long-lasting problems with many aspects of emotional and social functioning.

1) Symptoms:
The smptoms are in particular insomnia, irritability, extreme irritability, sudden and impulsive outbursts, difficulty concentrating and an exaggerated the outsider appears vigilance.

2) What causes PTSD?
Virtually any trauma, defined as an event that is life-threatening or that severely compromises the physical or emotional well-being of an individual or causes intense fear, may cause PTSD. Such events often include either experiencing or witnessing a severe accident or physical injury, receiving a life-threatening medical diagnosis, being the victim of kidnapping or torture, exposure to war combat or to a natural disaster, exposure to other disaster (for example, plane crash) or terrorist attack, being the victim of rape, mugging, robbery, or assault, enduring physical, sexual, emotional, or other forms of abuse, as well as involvement in civil conflict. Although the diagnosis of PTSD currently requires that the sufferer has a history of experiencing a traumatic event as defined here, people may develop PTSD in reaction to events that may not qualify as traumatic but can be devastating life events like divorce or unemployment.

3) What are the most common dangers associated with post-traumatic stress disorder?
Post-traumatic stress disorder or PTSD can really affect a lot of a person's areas of life. The dangers of post-traumatic stress disorder or PTSD are impairment in social and occupational functioning. If post-traumatic stress disorder or PTSD goes untreated, it's not uncommon for people to become estranged from their families; to lose those important relationships. If there's a lot of irritability and problems with concentration, this obviously will impact a person's ability to perform will at work. Other dangers of post-traumatic stress disorder or PTSD include development of other disorders such as major depression. This has its own set of dangers. People with post-traumatic stress disorder or PTSD are also more prone to develop substance abuse as they deal with problems with sleep, and will often turn to alcohol, or pot, or other kinds of sedatives to help them sleep or to help decrease the anxiety symptoms. This can just add together to create a downward spiral which can be very damaging.

4) What are the common treatments for post-traumatic stress disorder?

It is important to get treatment for post-traumatic stress disorder, and important, I think, that you are taking a comprehensive approach. This would often include medication and physcotherapy.