ANONYMOUS wrote: Hi, near the top of that page it states "certain files depend on others and, if one changes, it triggers the "rebuilding" of others". In our example if, say, calcmarks.h changes, it does not trigger the rebuilding of calcmarks.c, and calcmarks.c remains unchanged. However, calcmarks.o is dependent on calcmarks.h, because if calcmarks.h changes, then calcmarks.o need rebuilding (by compiling calcmarks.c) Similarly, the whole program is dependent on each of the object files - if any of them changes, then we need to link the object files to form the executable. This is shown in the diagram on the same page, where the arrows show the dependencies. Hope this helps,