a package management framework for the Ruby programming language
An application or library is packaged into a gem, which is
a single installation unit.
RubyGems entirely manages its own filesystem space, rather
than installing files into the "usual" places. This enables
greater functionality and reliability.

Using RubyGems, you can:
- download and install Ruby libraries easily
- not worry about libraries A and B depending on
  different versions of library C
- easily remove libraries you no longer use
- have power and control over your Ruby platform!

You could browse source code at https://github.com/rubygems/rubygems
