In the previous chapter, we created a program where every structure and every function in each source file was available to every other source file. Such accessibility is not always desirable, especially in very large programs with many source files.
In this chapter, we learned about the three components of scope: visibility, extent, and linkage. For variables, we applied those concepts to various levels of scope: block/local, function parameters, file, and global scope. We then learned how these concepts applied to the five storage classes: auto, register, extern, static, and typedef.
We saw how functions have simpler scoping rules than variables. We saw how header files allow functions to be global across multiple files, wherever the header is included. We then applied the static keyword to functions to limit their scope to just a single compilation unit.
