The document explains OpenGL as a software interface to graphics hardware, detailing its approximately 150 commands for creating interactive 3D applications. It defines prefixes and suffixes in relation to OpenGL, noting that prefixes help avoid naming conflicts while suffixes denote data types and their sizes in C language. Various OpenGL data types and their corresponding C types are listed, such as glbyte for 8-bit integers and glfloat for 32-bit floats.