RSS (Really Simple Syndication) allows users to subscribe to frequently updated content like news headlines and blog posts. When a site publishes new content, RSS feeds deliver brief summaries to subscribers without them having to manually check the site. RSS feeds are automatically detected and displayed by most web browsers and can be read through an RSS reader, which aggregates feeds from multiple sites in a single interface. This allows users to easily keep up with updates from their favorite sources in one centralized location.