An RSS Reader is a tool that allows users to subscribe to and aggregate content from various websites in one place. It uses the Really Simple Syndication (RSS) format to deliver updates from blogs, news sites, and other online content sources. This makes it easier for users to stay informed without having to visit each site individually. Users can add their favorite websites to the RSS Reader, which then automatically fetches and displays new articles or posts. Popular RSS Readers include applications like Feedly and Inoreader, which offer features such as categorization and offline reading for convenience.