mime-types is a comprehensive Node.js module for inferring MIME types from file extensions and vice versa. Its robust database of MIME types ensures accurate content-type detection for web servers, file handling, and more. It allows developers to easily look up related MIME types with extensions and extensions with MIME types, simplifying content delivery and ensuring proper interpretation by browsers and other applications. It's lightweight, dependency-free, and essential for any project working with file formats.