The text provides a comprehensive tutorial on building a RESTful API using Nest.js, a scalable server-side Node.js framework developed with TypeScript and inspired by Angular.js. The guide walks through the entire process from setting up a Nest.js application, configuring database connections with MySQL and TypeORM, to creating modules, services, controllers, and data transfer objects (DTOs) for handling product-related operations such as creating, retrieving, editing, and deleting products. Additionally, it covers testing the application's business logic using Nest.js's built-in testing infrastructure with Jest, and automating these tests using CircleCI for continuous integration. The tutorial emphasizes the importance of structuring applications using Nest.js's modular design and offers insights into test-driven development practices, with references to source code on GitHub for further exploration.