Software rendering is the process of generating an image from a model by means of computer software. In the context of computer graphics rendering, software rendering refers to a rendering process that is not dependent upon graphics hardware ASICs, such as a graphics card. The rendering takes place entirely in the CPU. Rendering everything with the (general-purpose) CPU has the main advantage that it eliminates the need of a graphics card for rendering, but the disadvantage is that a CPU is not designed specifically for graphics rendering in the way a graphics card is which leads to slower rendering times.
Rendering is used in architecture, simulators, video games, movies and television visual effects and design visualization. Rendering is the last step in an animation process, and gives the final appearance to the models and animation with visual effects such as shading, texture-mapping, shadows, reflections and motion blur. Rendering can be split into two main categories: real-time rendering (also known as online rendering), and pre-rendering (also called offline rendering). Real-time rendering is used to interactively render a scene, like in 3D computer games, and generally each frame must be rendered in a few milliseconds. Offline rendering is used to create realistic images and movies, where each frame can take hours or days to complete, or for debugging of complex graphics code by programmers.