The document discusses various graphics concepts used in C programming including:
1. Color constants, fill patterns, graphics drivers, errors, and modes that are used in graphics functions.
2. The functions closegraph, detectgraph, getbkcolor, getcolor, getmaxx, getmaxy, getpixel, getx, gety, grapherrormsg, graphresult, initgraph, outtext, outtexttxy, putpixel, setbkcolor, setcolor, and setfillpattern and their purposes.
3. initgraph initializes the graphics system by loading a driver and putting the system into graphics mode, while closegraph deallocates memory and restores the original screen mode.