Ruby on Rails is a web framework in the Ruby programming language. Ruby on Rails has a set of out-of-the-box tools that allow you to quickly complete basic task
Ruby is quite concise and does not require a lot of backend code, which allows developers to quickly create and run prototypes (this makes Ruby similar to Python). Ruby rose in popularity in the early 2000s but has declined markedly since then.
Ruby is an open source language, which means it can be modified and supplemented.
What you can do in Ruby
Ruby allows you to:
automate repetitive tasks;
create web applications;
write mobile applications and games;
create prototypes.
Which companies use Ruby
Airbnb, Codecademy, TaskRabbit, Kickstarter, RapGenius, Scribd, AngelList.