4.1 Python Program Structure

By way of introduction, let's first get a clear picture of how this chapter fits into the overall Python picture. From a more concrete perspective, Python programs can be decomposed into modules, statements, expressions, and objects, as follows:

1. Programs are composed of modules.

2. Modules contain statements.

3. Statements contain expressions.

4. Expressions create and process objects.

We introduced the highest level of this hierarchy when we learned about modules in Chapter 3. This part's chapters begin at the bottom, exploring both built-in objects, and the expressions you can code to use them.