Strapi is a versatile headless CMS for Node.js that facilitates API creation with a user-friendly interface for defining content types and managing user roles. It supports both RESTful APIs and GraphQL, and is compatible with SQL and NoSQL databases, allowing easy database switching through environment variables. The guide outlines steps to set up a Strapi environment, create database schemas, and implement JWT-based authentication, all while integrating a Gatsby frontend. Strapi's content builder plugin simplifies schema creation, independent of the database used, and its authentication system distinguishes between public and authenticated user roles for content access. The tutorial also details customizing controllers for comment management and switching from SQLite to PostgreSQL for production use. Strapi is praised for its customizability and support for various frontend frameworks like Nuxt, React, and Angular, making it an effective tool for developing backend APIs.