Ruby was a rather obscure object-oriented dynamically typed "scripting language" until it suddenly got a lot of notice due to the appearance of the Rails Web application framework. The combination quickly became known as Ruby on Rails, I suppose because that creates a better image than Rails on Ruby - in any case, we can use the "RoR" acronym.
As an interpreted language, Ruby performance is not particularly spectacular, but due to the popularity of RoR, serious effort is being applied to change this. The original interpreter was written in C, but there are now versions in Java (JRuby), .NET ( IronRuby) and probably other languages. The current stable version of Ruby is 1.8.6, released in March of this year. A significant update to version 1.9 and a major upheaval update to version 2.0 are anticipated.
