This tutorial guides developers in building an automated appointment reminder system using Go programming language and Twilio's Programmable Messaging API. The system aims to reduce no-shows by sending reminders to clients via SMS, improving the efficiency of appointment-based businesses. To follow along with this tutorial, developers need to have Go 1.22 or above installed on their computer, a Twilio account with an active phone number, and access to a MySQL database. They will also create a new Go project, install required dependencies such as gorilla/mux, the Go MySQL driver, cron, and GoDotEnv, provision a database, retrieve Twilio credentials, and create the application logic. The system includes functions for displaying the HTML form used to book an appointment, processing form submissions, retrieving appointments scheduled for the following day, and sending reminder SMS messages. Developers will also define application routes, create a user interface for patients to fill in their appointment details, test the application, and schedule reminders using cron jobs.