An unreal experience that feels real to the person is called a hallucination. It could be visual, auditory or tactical. These symptoms may be due to an illness, medication induced or psychological problem. Types of hallucinations are: 1) visual hallucinations: seeing things or people that aren't there. 2) olfactory hallucinations: smelling things without any stimulus. 3) Gustatory: taste of things without a stimulus. mostly a metallic taste 4) Auditory: hearing voices 5) tactile: feeling of touch or movement without stimulus. Causes of the condition include: substance abuse (hallucinogenic like LSD, PCP), lack of sleep, Medication induced (anti epileptics), high fever, migraine, isolation, seizures, epilepsy and chronic illnesses. Diagnosis is done by ruling out medical causes. The treatment options include: counselling, medication withdrawal and medical therapy if required (anti psychotics, anti-epileptics).