CUDA = Compute Unified Device Architecture
CUDA is a technology, feature, parallel computing platform and API that created by NVIDIA engineers. It also addition of C language. Also, the CUDA platform is designed to work with programming languages such as C, C++, and Fortran. This accessibility makes it easier for specialists in parallel programming to use GPU resources. That's why cuda is becoming so popular. On the other hand, to write OpenGL or Direct3D programs that required advanced skills in graphics programming. With cuda technology, we can make more efficient use of the GPU cores and use the cores in the GPU based process.
As we know, In computer games or that industry GPU's are very important for fps and quality. Day by day the industry use new technologies and games wants much more graphics power to run games properly. GPU's main purposes of games are graphics rendering and physical calculations (PhysX).
CUDA has also been used to accelerate non-graphical applications in computational biology, cryptography and other fields by an order of magnitude or more. This field very important because of MINING. Zcash and Etherium is very important and to produce these coins, we use our gpu power. Especially to mine zcash, CUDA technology uses very much.
Nowadays, many Nvidia gpu's support cuda features and technologies. No doubt that, many cuda versions are available and their performance different from each other.