This lesson was short, but it’s important because it introduced you to the major components of a C program. You learned that the single required part of every C program is the main() function. You also learned that a program’s real work is done by program statements that instruct the computer to perform your desired actions. You were also introduced to variables and variable definitions, and you learned how to use comments in your source code.
In addition to the main() function, a C program can use two types of subsidiary functions: library functions, supplied as part of the compiler package, and user-defined functions, created by the programmer. The next few lessons go into much more detail on many of the parts of a C program that you saw in this lesson.