A delusion is a firm false belief that continues to exist despite evidence to the contrary. The belief can be regarding any usual aspect of the person’s life but is not believed by anyone else except him since it is not true. Examples may include, infidelity of spouse, that one is being harmed or one is being loved by someone. A person with a delusion will be convinced that his/her belief is true and misinterpret new information to confirm the delusion. However, other than the delusion, the person may be able to function adequately in other aspects of life. Thus, a delusion may exist for a long time before it causes a crisis or conflict.