Some Things a Ruby Module Can Do for You

In many ways, modules act a lot like classes, although you can't actually instantiate them. There are quite a number of reasons to put code, classes, and other objects inside modules. These include:

1. Namespacing, to prevent collisions between same-named constants, classes, methods, and variables.
2. The ability to compose or extend classes, rather than relying on Ruby's single-inheritance model by "mixing in" modules. That's why modules in Ruby are often called mixins.
3. The ability define class and module level methods that don't need to be instantiated to be used.
4. The ability to hook the inclusion of modules to create certain behavior when you mix them into other classes.
5. Support for autoloading.
6. The ability to adjust the lookup order of the class hierarchy depending on whether you include or prepend a module.
7. Support for refinements (see Module#refine and Module#using).

There are likely other things that I haven't thought about in this quick, off-the-cuff answer. However, modules are essential building blocks for gems and larger Ruby applications, and understanding them is worth doing, especially if you're planning to grow beyond basic scripting with Ruby.