A diorama is a partially three dimensional model of a landscape typically showing historical events, nature scenes, cityscapes, etc. for purposes of education or entertainment. The term was patented by Louis Daguerre in 1822, for a kind of rotating display. Frank M. Chapman , a curator at the American Museum of Natural History during the late 19th and early 20th century, helped popularize the style commonly seen today.

Dioramas typically will use a tilted plane to represent what would otherwise be a level surface, a painted background of distant objects, and often employ false perspective, carefully modifying the scale of objects placed on the plane to reenforce the illusion through depth perception of viewing a larger space - representations of objects (of identical real-world size) placed further from the observer are smaller than those closer. Often the distant painted background or sky will be painted upon a continuous curved surface so that the viewer is not distracted by corners, seams, or edges. All of these techniques are means of presenting a reasonably realistic view of a large scene in a compact space. A photograph or single eye view of such a diorama can be especially convincing since in this case there is no distraction by the binocular perception of depth.

One of the largest dioramas ever created was a model of the entire state of California built for the San Francisco World Fair and that for a long time was installed in San Francisco's Ferry Building.

More typical are the dioramas used to present mounted ("stuffed") animals, birds, and simulated plants to form a realistic representation of the animals where they are found in nature. These may usually be seen in the natural history museums found in most large cities.

Miniature dioramas are used to represent scenes from historic events (e.g., tin soldiers arranged in a display depicting a famous battle). A typical example of this type are the dioramas to be seen at the Norges Hjemmefrontmuseum (Norwegian Resistance Museum ) in Oslo, Norway.

Also the landscapes built around model railways are dioramas.