Ruby on Rails is an open-source server-side web application framework with an MIT license. While Ruby on Rails is written in Ruby, a dynamic, general-purpose programming language from Japan, RoR is, in fact, a framework, not a language. Many entrepreneurs and non-developers often confuse the two, thinking of Rails when hearing Ruby but rarely the other way around.
This may be brought on by the fact that the most of Ruby developers use the Ruby on Rails framework for development.
Ruby gained momentum as a programming language following the launch of Ruby on Rails.