Atom: The name Atom applies to a pair of related Web standards. The Atom Syndication Format is an XML language used for web feeds, while the Atom Publishing Protocol is a simple HTTP-based protocol for creating and updating web resources. Web feeds allow software programs to check for updates published on a website.
Substack: Online platform that provides publishing, payment, analytics, and design infrastructure to support subscription newsletters.
RSS: RSS is a web feed that allows users and applications to access updates to websites in a standardized, computer-readable format. These feeds can, for example, allow a user to keep track of many different websites in a single news aggregator.