Agoraphobia is an anxiety syndrome in which patients experience severe anxiety or distress in certain places or situations. This can lead to the avoidance of these situations. The places often represent those from which escape might be difficult or embarrassing e.g., public transport, supermarkets, crowds, or lifts. However, symptoms can also occur when the patient is alone in any place where they anticipate that they will be unable to obtain help should "the worst" happen. It often starts after unexplained spontaneous symptoms of anxiety or panic attacks, and the fear of anxiety symptoms rather than the actual attacks becomes predominant leading to a heightened state of anticipation.