Cheerio is a fast, flexible, and lean implementation of core jQuery designed specifically for the server. It parses HTML and XML documents, providing a simple API for traversing, manipulating, and rendering them. It's perfect for web scraping, data extraction, and server-side HTML processing where a full browser environment isn't required. Cheerio offers a familiar jQuery-like syntax, making it easy to work with existing jQuery knowledge while providing significant performance benefits in Node.js.