Webmention is a web standard for mentions and conversations across the web, a powerful building block that is used for a growing federated network of comments, likes, reposts, and other rich interactions across the decentralized social web.

I was introduced to it via Return of Love, Death, Robots - Mark writes

I love idea of this. OH MAN I love, even more, ability to reply to a discourse thread with a link to my blog post of my reply!!