The tutorial outlines the process of integrating Twilio's texting functionality into a to-do list application using RapidAPI. It begins with acquiring Twilio credentials and setting up webhooks to handle incoming SMS messages via the RapidAPI platform, which simplifies the integration by providing access to multiple APIs through a single SDK. The guide demonstrates how to parse incoming texts, manage function callbacks, and update the to-do list in a database using MongoDB paired with Mongoose. The application sends updated lists back to the user's phone by utilizing functions like getNoteToPrintTwilio and sendListAsText. The tutorial emphasizes the ease of using RapidAPI to streamline API integration, allowing developers to focus more on coding rather than setting up new libraries.