Visualization is a very common technique used in hypnotherapy and NLP. It involves creating mental images or pictures in a persons mind.

Visualization is an experience that, on most occasions, significantly resembles the actual experience of perceiving some object, event, or scene in the physical world, yet is not actually present to the senses.

Visualization is commonly used as a form of visual rehearsal, allowing a person to imagine themselves in the future as having or doing whatever it is they want to have or do now.  Visualization can also be used as a form of self hypnosis.

Common examples of mental imagery include daydreaming and the mental visualization that occurs while reading a book. Producing an image in our minds can be a voluntary act, so it can be characterized as being under various degrees of conscious control.