The author, Greg Baugues, created a Sinatra app in Ruby to provide Christmas carol lyrics via text message. He used Twilio for the texting functionality and built the app using Sinatra's stripped-down nature to quickly develop it. The app allows users to send a "carols" text to 907.312.1412 and receive a menu of song options, followed by the lyrics when selecting a song. The author started with a lot of hardcoded code but refactored it for better maintainability and readability. After testing and deploying the app on a VPS using Dokku, he made the production URL available to share with others.