Gems are very useful for not reinventing the wheel and avoiding duplication. That’s basically it. Many Ruby developers create and publish awesome gems which address specific requirements, solve specific problems or add specific functionality. Anyone who comes across similar requirements or problems can use them and eventually improve them. That’s the combined awesomeness of Ruby’s strong open-source foundation and extreme flexibility. Anyway, you’re reading this article… so you’ve probably understood the concept and grasped its usefulness long before reading this paragraph.