FriendlyId is an add-on to Ruby’s ActiveRecord that allows you to create clean, human-readable URLs and work with strings as if they were numeric ids:
Change is the only constant - Heraclitus (Philosopher)
Sinatra is a DSL (Domain Specific Language) implemented in Ruby that’s used for writing dynamic web applications. Sinatra is designed to be lightweight and flexible. It is a “Human Interface” to Rack (a powerful middleware between the application and the server).