This tutorial demonstrates how to build a CLI application using Deno, a new runtime environment for JavaScript that provides capabilities similar to Node.js without the heavyweight package deployment and complex package management. The application uses Twilio's Programmable SMS API to send messages and reports on delivery status. The tutorial shows how to read command line arguments in Deno using the yargs library, register alias shortcuts, and fallback to environment variables when necessary. It also covers how to use the TwilioSMS helper method to send SMS messages with a predefined message request object. By following this tutorial, developers can create a simple CLI application that sends SMS messages using Twilio's API.