Question
Why would I select specific variables/behavior to load into a program instead of defining said variables/behavior in the program itself?
Answer
A few reasons why we would want to select specific variables and behavior to load into a program: they allows us to write less code, there is less room for error (when the selected variables/behaviors are already working), bugs are easier to find and fix, along with many other reasons.
This ability to select specific variables/behavior to load into a program, and potentially multiple programs, is part of what make modules so great!