one thing i am still a little unsure about. In the beginning C book he says that the Compiler is instructed to "include" in our program the file stdio.h

Since you said "the preprocessor—the first tool to examine source code when it is compiled—to substitute for that line the entire text of the file or other entity to which it refers."

So when he says the compiler is instructed to "include" does he just mean that the compiler will convert the code that the preproccesor adds into machine code along with the rest of the file??

Also if the preproccessor is adding the header file to the source file then what files does the linker link when it creates the exe file since the header file is already included