One of the greatest things about Ruby is the way it can be extended by other third-party modules. These modules are called "gems." All gems are free and open source, making them extremely robust. There are about 7,900 of them, in fact, with over 19 billion downloads. Anyone can create a gem, but like Drupal, duplication is limited, and developers will contribute to an existing gem before recreating one that exists already just to add one small feature.
Fun fact! Did you know Rails is a gem? Yes, in fact, the Rails framework is just a gem that can be downloaded and installed to run your application.