This first article in a series on portable multithreaded programming using OpenCL™ briefly discusses the thought behind the standard and demonstrates how to download and use the ATI Stream software development kit (SDK) to build and run an OpenCL program.
view at The Code Project (http://www.codeproject.com/Articles/110685/Part-OpenCL-Portable-Parallelism)
The thought behind OpenCL
The big idea behind OpenCL is a portable execution model that allows a kernel to execute at each point in a problem domain. A kernel is a function declared in a program and executed on an OpenCL device. It is identified by the __kernel qualifier applied to any function defined in a program. Kernels can operate in either a data-parallel or task-parallel fashion.