Application software on Integrate Circuit.
There was CPU Mining which was replaced with GPU that 100x faster
Then there was FPGA mining that is more energy efficient than GPU.
Now ASIC which is about 50x faster than GPU and FPGA will render both a waste of energy.
My suggestion is that you read up on ASIC and not buy any GPU's.
Look at
www.butterflylabs.comIf you haven't read that blog noted above, read it. there are some other good posts on that site as well.