Ruby has a package manager for its libraries or gems. It should be a concept familiar with other package managers like apt, yum, or yast.

Gems are libraries for Ruby. Many gems are built to extend Ruby on Rails and are a great way to add functionality to your application. You can see available gems at RubyGems.org. In order to install Rails, you typically need Rubygems installed via a "gem install rails". To get a pre-release version of Rails, you can run "gem install rails --pre".

Gems for use in your Rails application are included in your Gemfile. Once you've specified the gems, run "bundle" or "bundle install" to get the gems you need. You can set up a test group to include testing and debugging libraries and exclude them in production environments.

Bundler handles dependency problems by evaluating dependencies and then chooses the libraries that meet all dependencies.