OAuth4 (and OAuth4R)

This document provides an overview of OAuth and how to implement it using the OAuth4R Ruby gem. OAuth is an open protocol that allows secure API authorization in a simple standard way. It allows websites or applications to access user information on another site without needing the user's password. The document explains the OAuth workflow including registration, request tokens, authorization, and access tokens. It then demonstrates setting up a sample Rails application using OAuth4R to authorize a "consumer" application to access protected user resources from a "provider" application.