The MERN stack, consisting of MongoDB, Express, React, and Node.js, is a popular technology stack for modern web development due to its use of JavaScript across the entire stack, which simplifies development by allowing a unified codebase for both front-end and back-end operations. MongoDB offers a flexible, document-based database system that integrates well with JavaScript, while Express and Node.js form the back-end framework for handling server-side logic and API requests. React powers the front end, enabling the creation of dynamic, component-based user interfaces. This stack is particularly suited for building fast, dynamic single-page applications (SPAs) and is favored by solo developers and small teams for its flexibility and the large supportive community. While the MERN stack excels in scenarios that require rapid development and a flexible schema, it is less ideal for applications that require complex relational data operations or server-side rendering for SEO purposes, where alternatives like the PERN stack or frameworks such as Next.js might be more appropriate. The tutorial also explores integrating the MERN stack with Contentful, a content management system, to streamline content delivery and management, allowing developers to focus on building unique app functionalities.