Express is a web application framework for Node.js that simplifies the process of building web servers and APIs. It provides a robust set of features for handling HTTP requests, routing, and middleware, making it easier for developers to create dynamic web applications. With its minimalist design, Express allows developers to focus on writing their application logic without getting bogged down by unnecessary complexity. It supports various templating engines and can be easily integrated with databases, making it a popular choice for both small projects and large-scale applications.