Here is a summary of the provided text in one paragraph: To create a robust and scalable application, API data validation is crucial. This tutorial demonstrates how to validate user data using Strapi's built-in validator called Yup. We created a custom plugin for managing user registration and login functionality, including authentication and authorization. The plugin uses Strapi's built-in `@strapi/utils` library to handle errors and ensure data integrity. We also developed a custom controller for the Blog collection to handle CRUD operations, including creating, reading, updating, and deleting blog posts. Additionally, we created an HTML frontend using basic HTML templates to demonstrate API data validation in action. The tutorial covers key aspects of Strapi development, including plugin creation, custom controller development, and user authentication/authorization.