What does HLSL stand for? Why was it created? How does an HLSL effect file look like? What can you do with HLSL? What do float4x4, TEXCOORD0 or compile ps_3_0 mean? The answer to the first question is simple: HLSL means High Level Shader Language. This answer by itself might raise a few questions. The answers for these and a few other questions will be found in this article.
You will first learn about the history of HLSL and why it came to existence. After that, you will see the basic structure of an HLSL effect file, and learn about the different elements of the language. Finally, after looking over the language’s basics, you will see the template effect file that XNA gives to us.
Full article at Sgt. Conker