It is a feeling of agitation and distress. Some anxiety is natural and helps to keep you mentally and physically alert, but too much may cause physical distress, emotional upset, and concentration difficulties. Anxiety occurs in a wave, so it will increase from the time you first recognize it, come to a peak, and then naturally subside.
Anxiety has physiological, behavioral, and psychological effects.
Physiological reactions may include rapid heartbeat, muscle tension, queasiness, dry mouth, or perspiration. Behavioral reactions may include and inability to act, make decisions, to express yourself, or to deal with everyday situations. You might also experience mental blocking, which means going blank on questions an possible remembering the correct answers as soon as the exam is over. Psychological reactions may include feelings of apprehension, uneasiness, upset, and self-doubt. Usually there is some real or perceived activating agent.