Once we have compiled our shaders and before we can actually install them into the OpenGL pipeline, we need to link them together into a shader program. Among other things, the linking step involves making the connections between input variables from one shader to output variables of another, and making the connections between the input/output variables of a shader to appropriate locations in the OpenGL environment.

Linking involves steps that are similar to those involved in compiling a shader. We attach each shader object to a new shader program object and then tell the shader program object to link (making sure that the shader objects are compiled before linking):