OpenGL maintains a large set of state variables. State variables hold values that remain active until changed through a function call designed to make such a change. The current drawing color is one such state that we set/change through a call to glColor. Other OpenGL states, as seen in this example, are the current line width, the current clear color and the current projection window boundaries. We generally write one function (init in our example) that sets states we use in our program and will not change.