Webmention - Wikipedia
This W3C recommendation documents the Webmention protocol, which lets a site notify another when it links to it, enabling decentralized comment/reply threads across independent domains—essentially federated commenting without a central platform. Grown out of the IndieWebCamp movement, it deliberately simplifies earlier linkback mechanisms like Pingback by using plain HTTP form-encoded requests instead of XML-RPC, and it also handles edge cases like edited or deleted source pages. Worth keeping as a reference for implementing IndieWeb-style interlinking or understanding how it compares to Pingback, Trackback, and Refback.