This refers to the use of images of differing resolutions depending on the perspective distance between the user and the object in a graphical scene. At close range, !he image is used at high resolution to reveal all detail, but as the distance increases, since detail is no longer important, a low-resolution version of the image is used.

Doing so saves on resources and doesn't affect the visual quality of the creation. A mipmap is a table that contains the different versions of the various images used in the scene.