Visualisation is the exercise of rendering mental images, or, seeing with your mind's eye. It is a skill closely related to mental constructs, as it is required for the creation of any mental construct with a visual component. Visualisation is commonly used in every-day life, when recalling visual memories, imagining how unknown things or places might look, or daydreaming.
Visualisation in practice
Visualisation is a common activity in day to day life. Visualisations are usually seen in the mind's eye, and can happen when imagining something, solving a problem, daydreaming, recalling a memory, among other things. These Visualisations can vary in clarity, depending on the person, and the ability of the person to render mental images. See: Forcing.