Ruby on Rails, often referred to as Rails, is an open-source web application framework written in Ruby. Known for its convention over configuration and don't repeat yourself (DRY) principles, Rails simplifies and accelerates the development of database-backed web applications.

A template or theme refers to a pre-designed layout or structure that provides a basic framework for building a specific type of application or website. It typically includes good design, placeholder content and functional features, allowing developers to customize and fill in the details according to their specific needs.