An XML schema used to update people about changes in blogs, podcasts, and similar stuffs.
An RSS file summarizes recent updates on a site. Feed reader apps, such as Feedly (web), Fraidyc.at (web), Newsflow (Windows), FeedReader (Linux and Web), or NetNewsWire (macOS), let you subscribe to all the sites you like. This lets you read updates on your own schedule.
You can also generate your own RSS feeds so others can follow you.