Ruby is an intuitive, object-oriented scripting language originally created in the 1990s by Yukihiro Matsumoto. Check out www.ruby-lang.org to learn more.
Ruby on Rails is a web application framework written in Ruby. It was created in 2004 by David Heinemeier Hansson and optimized by hundreds of other developers since then. It serves as an authoring environment to facilitate the rapid (and fun!) development of robust web applications. For more information, check out the Ruby on Rails homepage.