Hallucinations are experiences where one's senses are deceived and the unreal seems real.
Hallucinations are common psychotic symptoms of schizophrenia, schizoaffective disorder, bipolar disorder, post-partum psychosis and other psychotic disorders.
The most common hallucinations are auditory, where a patient hears voices or sounds that do not really exist. Visual hallucinations (seeing images that aren't there) are the next most common type.
For more, see What Are Hallucinations?.

