Anxiety is an emotion characterized by an unpleasant state of inner turmoil, often accompanied by nervous behaviour such as pacing back and forth, somatic complaints, and rumination. It is the subjectively unpleasant feelings of dread over anticipated events.
Anxiety is a feeling of uneasiness and worry, usually generalized and unfocused as an overreaction to a situation that is only subjectively seen as menacing. It is often accompanied by muscular tension, restlessness, fatigue and problems in concentration.
Anxiety is closely related to fear, which is a response to a real or perceived immediate threat; anxiety involves the expectation of future threat. People facing anxiety may withdraw from situations which have provoked anxiety in the past.

Symptoms
Neurological, as headache, paresthesias, fasciculations, vertigo, or presyncope.
Digestive, as abdominal pain, nausea, diarrhea, indigestion, dry mouth, or bolus.
Respiratory, as shortness of breath or sighing breathing.
Cardiac, as palpitations, tachycardia, or chest pain.
Muscular, as fatigue, tremors, or tetany.
Cutaneous, as perspiration, or itchy skin.