Ruby is an interpreted, dynamically-typed, object-oriented programming language. It has a simple, natural syntax that enables developers to create applications quickly and easily. It also includes the easy-to-use RubyGems packaging utility for customizing a Ruby installation with additional plug-ins.
Rails is a web application framework that leverages the simplicity of Ruby and eliminates much of the repetition and configuration required in other programming environments. With Rails, you can create database-backed web applications, complete with models and tables, by running a few one-line commands.
To learn more about Ruby on Rails, see Ruby on Rails.