A hallucination is a image that you have when you are conscious, but isn't real. The most common hallucination is an audio hallucination. The hallucination doesn't have a source. They are usually caused by stress, medication, or excessive drinking and drug usage.
A hallucination is a perception of something that is not actually present, such as seeing, hearing, or feeling something that is not real. It can occur in any of the senses and can be caused by various factors such as mental health conditions, substance abuse, or neurological disorders.