Ruby Gems are packages or libraries that extend the functionality of the Ruby programming language. They allow developers to easily share and reuse code, making it simpler to add features to applications without having to write everything from scratch. Each gem can contain code, documentation, and tests, and they are typically hosted on the RubyGems.org website. To use a gem, developers can install it using the Bundler or gem command-line tools. This process helps manage dependencies and ensures that the correct versions of gems are used in a project. Overall, Ruby Gems play a crucial role in the Ruby ecosystem, promoting collaboration and efficiency.