Plex plugins, also known as Plex channels or extensions, are add-ons that expand the functionality of the Plex media server and player. These plugins offer additional content, features, and customization options beyond what Plex offers out of the box. They allow users to access a wider range of media, integrate with external services, and enhance their overall media streaming experience. Plex plugins can provide various types of content, including online video streaming, music, news, podcasts, and more.