Here is another abbreviation for you. HDR is an abbreviation of High Dynamic Range. This is a technique giving images a wider range than the one captured by the camera. Artists use this as well. They simply paint or add things to the scope of the image they can see. In photography, the idea is to represent the scene as it is seen by the human eye.
Artists use to include objects they may see outside of their field of vision. They think the objects add interest so they add them in. In photography, HDR photos are created when multiple photos and different exposure values are combined.