Lumen is a command line tool that is part of the Laravel PHP framework. It provides a lightweight alternative to Laravel, focusing on building microservices and API-centric applications. Built on top of the Laravel components, Lumen retains the simplicity and elegance of its parent framework. With Lumen, you can develop fast and scalable applications that handle high loads and run efficiently. It offers a minimal footprint and optimized performance, making it ideal for microservice architectures. Lumen prioritizes simplicity and speed, providing a streamlined development experience to create small, fast, and powerful projects. It includes a powerful routing system, allowing you to define routes easily and map them to appropriate controllers. Lumen also offers a variety of essential features like middleware support, configuration management, caching, and database integration. It seamlessly integrates with other Laravel components and packages, enabling the use of a wide range of available tools and libraries. Overall, Lumen is a fantastic choice for developers who need a lightweight and high-performance PHP micro-framework for building powerful API-centric applications.