Graphics Processing Unit (GPU)
The GPU is the same thing as the Central Processing Unit on your computer, with two (main) differences: it is geared toward graphical computations, and it coordinates the work of the graphics card rather than the whole computer.
GPU is of the topmost importance when choosing graphics adapters (but not everything). The manufacturers NVIDIA and AMD/ATI have their own GPUs. The series to which the GPU belongs is displayed in big letters/numbers on the hardware boxes, such as Nvidia 9600 or ATI 4870. These numbers give a very detailed explanation of what’s inside.
In NVIDIA’s notation, the four numbers tell the following about the GPU (take 8600 for example).
First digit: The chronological series to which the GPU belongs, for a 8600 card, this is 8000 series GPU. It came out after the 7000 and before the 9000.
First digit: The series to which the GPU belongs, for a 8600 card, this is an 8000 series GPU.
Second digit: The segmentation. Usually 1,2, 3 and 4 point to entry level cards, 5 and 6 mid-range, 7 and 8 in the high-end GPUs.
Third and fourth digits: 99% of the time the last two digits will be 00.
When NVIDIA ran out of 4 digits with 9000 series, they switched to a 200 series. In the 200 series, the notation has changed slightly, 5 and 6 in the second digits point to entry-level cards, 6 point to mid-range and 8 and 9 point to the high-end.
In terms of features, the line-up is GS, GT, GTS and GTX in order from low performance to high performance.