What is GPU?
GPU is a a single chip processor with integrated transform, lighting, triangle setup/clipping, and rendering engines that is capable of processing a minimum of 10 million polygons per second.”
Purpose of GPU
As computations are increasing day by day and there is allot of load on general purpose CPU , and further if a user does graphic processing then due to huge load the general purpose CPU gets slow down and graphics are also not displayed as per the desire of user so to make independent general purpose CPU from graphic processing and display the graphics in good form this GPU is used hence the load over CPU is decreased and also user have a good graphics which is shown by this picture .
this picture shows that you can get realism by GPU further GPU can effectively process the 3D graphics which is used mostly now adays
Techno Talk Blog 