Anxiety is a condition of persistent and uncontrollable nervousness, stress, and worry that is triggered by anticipation of future events, memories of past events, or ruminations over day-to-day events, both trivial and major, with disproportionate fears of catastrophic consequences. Stimulated by real or imagined dangers, anxiety affects people of all ages and social backgrounds. When it occurs in unrealistic situations or with unusual intensity, it can disrupt everyday life. Some researchers believe anxiety is synonymous with fear , occurring in varying degrees and in situations in which people feel threatened by some danger. Others describe anxiety as an unpleasant emotion caused by unidentifiable dangers or dangers that, in reality, pose no threat. Unlike fear, which is caused by realistic, known dangers, anxiety can be more difficult to identify and alleviate.