Post-traumatic stress disorder or PTSD is a mental health condition that is triggered by either experiencing or witnessing a traumatic event. The symptoms of PTSD can range from flashbacks, mood swings, anxiety, nightmares, and intrusive memories of the event. Its symptoms can manifest within a month after the incident that caused it or years later, and the symptoms may vary from person to person. Post-traumatic stress disorder is commonly associated with people who have served in the military, but other traumatic experiences like being in a car accident.