The Twitter API (Application Programmming Interface) in Ruby on Rails is about as simple as you can get. Twitter is a RESTful Rails application. API calls that query for information are GET requests, while information that changes, creates or deletes information are POST requests. The commands themselves are the URL your program accesses. Twitter will return status codes in the HTTP response code, and data in the format of your choosing (HTML, XML, RSS, etc).
Coding Library: Ruby