eMule is a free and open-source peer-to-peer file sharing client that runs on Windows operating systems. It allows users to share and download various types of files, including music, movies, and software. One of its key features is its ability to handle large files efficiently through the use of a credit system, which rewards users who share files with faster download speeds. Additionally, eMule offers a search function, chat rooms, and the ability to preview files before downloading them.