4.1 Overview
In C, a storage class determines where functions and variables are stored, how long variables persist, and where functions and variables can be made visible. For functions, the key issue is visibility (scope) because the lifetime of a function is the lifetime of the program that contains the function. For variables, both lifetime and scope are of interest to the programmer.
Storage classes also shed further light on the distinction between declarations and definitions in C. In large programs, with the constituent functions ...