Graphics card also known as graphics processor, graphics chip, graphics processing unit (GPU) is of real importance to gamers and designers. This chip is responsible for processing all the graphical output we see on the monitor.
Graphics has its own processors, RAM (called VRAM or virtual RAM), cores, threads, etc. There are three different clocks of graphics chip. These are core clock, memory clock, shader clock. Core clock is the frequency of graphics processor, memory clock is the frequency of RAM of GPU itself and shader clock is the clock of whole of the architecture of Graphics card.
Graphics card can be the most expensive chip of one's computer.
Most expensive and most powerful graphics card in today's date is GTX TITAN X, being around 3000$ worth. The main difference between a graphics card and a processor is that the output of the processor is generally a single value while that of a graphics processor is multi valued. Hence if anyone is thinking of replacing graphics card with processor, it would be really good to know that it cannot be done.
Unlike processors, processing power of a graphics chip is assessed by the amount of FLOPS it could generate. Flops is an abbreviation used for Floating Point Operations per Seconds. Floating point numbers are those numbers which are written in scientific notations ,i.e., 1000 is written as 10 to the power of 3 or simply 10^(3), 0.0001 can be written as 10^(-4). Operation here can be called as a calculation using mathematical operators (+, -, x, /, %, etc.) and most of the graphics processors can produce upto some teraflops (10^12 floating point operations per second).