1. Modules
Programmers break programming problems down into smaller, reasonable units called modules, subroutines, procedures, functions, or methods
When you create a module or subroutine, you give the module a name that a calling program uses when the module is about to execute
A module can call other modules
Functions are a type of module

2. Creating Hierarchy Charts
A hierarchy chart illustrates module relationships
Does not tell you what tasks are to be performed within a module and thus does not show control flow.
Does not tell you when or how a module executes
Rather, identifies which routines exist within a program and which routines call which other routines
A hierarchy chart shows hierarchy, that is, subordinate-superordinate relationships. In particular, it shows which modules (functions) call which others.

3. Creating Hierarchy Charts (continued)

4. Numbering of Modules

5. Module Listing Order