As you may already know, there are multiple versions of OpenGL. Each version offers a standard set of functions while other functions may be marked as deprecated. What's more, graphic card manufacturers try to extend these standard OpenGL functions with so-called extensions. Some extensions are specific to graphic cards and have a prefix in their names. Other ones have become standardized over time. For instance, an extension for vertex shader programs is called ARB_vertex_program and it's provided by the OpenGL Architecture Review Board. There is also a vendor-specific version of this extension called NV_vertex_program provided by the NVidia company in their GPUs. Many extensions start with the vendor-specific version, then they are reworked by the OpenGL ARB. In the final stage, they may be incorporated into the core specification of OpenGL. There are other extensions with names starting with GLX or WGL prefixes, which indicates that these extensions are specific...