It was created by the OpenGL Architecture Review Board (ARB) to standardize GPU instructions controlling the hardware graphics pipeline.
The OpenGL Architecture Review Board (ARB) was formed in 1992, in part to establish standards for the GPU industry.
While 3D developers are now more likely to use a C-like, high-level shading language for GPU programming, ARB assembly has the advantage of being supported on a wide range of hardware.
Note however that some features, such as loops and conditionals, are not available in ARB assembly, and using them requires to adopt either the NV_gpu_program4 extension, or the GLSL shading language.
The GPU's vertex processor calculates all the pixels controlled by a set of vertices, interpolates their position and other properties and passes them onto its fragment process.