Anxiety is usually defined as a diffuse, vague, very unpleasant feeling of fear and apprehension. It becomes a disorder when an individual's predisposition, upon exposure to stressors, evolves into a disorder. This transition is marked by prolonged, intense, and unexplained fears, unpredictable panic attacks, and severe physiological symptoms (like shortness of breath, dizziness, and palpitations) that disrupt normal functioning, such as a person becoming unable to relax or refusing to move out of their house.

There are several major types of anxiety disorders:

1. Generalised Anxiety Disorder: This consists of prolonged, vague, unexplained, and intense fears that have no specific object. It is accompanied by hypervigilance (constantly scanning the environment for dangers) and motor tension, making the person restless, visibly shaky, and unable to relax.

2. Panic Disorder: This involves recurrent and unpredictable panic attacks characterised by feelings of intense terror and dread. Clinical features include shortness of breath, dizziness, trembling, palpitations, choking, nausea, chest pain, and a fear of going crazy, losing control, or dying.

3. Specific Phobia: This involves irrational fears related to specific objects, interactions with others, and unfamiliar situations.

4. Separation Anxiety Disorder: This is characterised by extreme distress when expecting or going through separation from home or other significant people to whom the individual is immensely attached.

5. Other Disorders: This category includes Selective Mutism, Substance/Medication-Induced Anxiety Disorder, and Anxiety Disorder Due to Another Medical Condition.