Panic disorder is very different from the normal fear or anxious reactions to stressful events. Panic disorder is a serious condition wherein the person experiences acute fear and nervousness along with physical symptoms such as a racing heart and sweating, for around 10 mins or so. When the panic attack strikes, the fear response is completely out of proportion for the situation, which often is non threatening. The worse part is that over time a person suffering from panic disorder starts developing a constant fear of having another panic attack, which affects the daily functioning and the quality of life.
The key symptom of panic disorder, apart from experiencing an panic attack, is the constant fear of having future panic attacks. The fear of panic attacks can lead the person to avoid places and situations where an attack has occurred or where they believe an attack could occur.