A renderer is a software program or hardware device responsible for selecting the color of each pixel in a frame. Often these frames are shown in rapid succession to create an animation.

A 3D renderer takes as input a description of geometric primitives (often polygons) along with a the coordinates and viewing direction of a virtual camera, all of which are given in 3D "xyz" coordinates.

3D renderers can roughly be divided into two categories: photorealistic and real-time. RenderDotC falls into the photorealistic category.

The primary goal of photorealistic renderers is to generate images so convincing that they could be mistaken for photographs. They do so by capturing many details of real world photography (accurate lighting, shadows, textures, blurs, etc.) while avoiding the telltale signs of computer generated imagery (jaggies, aliasing, and other artifacts).

Real-time renderers, on the other hand, prioritize the speedy generation of images so that animations can be achieved right before the user's eyes. This usually involves the assistance of specialized graphics hardware.

While claims have been made that certain renderers can create photorealistic imagery in real-time, the fact is that a large margin still exists between the complexity of scenes rendered for films and what today's real-time renderers can handle. Projections indicate that this will continue to be the case for at least 20 years.