A graphics processing unit specializes in parallel arithmetic processing. It is housed on a chip that uses those calculations to render an image to a screen.

 VRAM, which is a special kind of DRAM (dynamic random access memory)  is dual ported and operates faster than normal RAM. Dual ported means that data can be read and written simultaneously. The bus between main memory and the GUP memory can be up to 256 bits wide. This means that you can move massive amounts of data. The data is then passed from the CPU to the GPU to be manipulated and then the CPU sends instructions to tell the GPU what is to be done to the data. the GPU will then manipulate that data and send it to VRAM and then can be used to display not. A copy of the manipulated data will be sent back to the CPU.