What is the purpose of the 'serve' method in Express.js?

The purpose of the 'serve' method in Express.js is to efficiently manage static files within a web application. This is essential for serving assets such as HTML files, CSS stylesheets, JavaScript files, images, and other media directly from the server to the client. By using middleware like express.static, developers can specify a directory from which the static files are served, allowing for better organization and access to resources that do not change frequently.

This functionality is crucial for the performance of web applications as it minimizes server-side processing for these files, enabling faster delivery to users and improving the overall user experience. Static file serving helps keep the server's workload focused on more dynamic tasks, such as API requests, while efficiently handling the delivery of unchanging content.