Without defining them, we've been using modules since Chapter 1. These are files that contain Python statements and definitions (classes and functions) and can be imported into other modules or into the main module. Module files are identified by the suffix .py.
If you're a programmer coming from a Java background, you may think that a module is similar to a package. Once you work with Python modules for a while, you may think of them more as a cross between a package and a final public class (with all static variables and a private constructor).
The import statement allows you to import classes, functions, and variables from one module into the current module's namespace. Table 5-1 describes its forms. Here is an example module, ...