"Webmention is a simple way to notify any URL when you mention it on your site. From the receiver's perspective, it's a way to request notifications when other sites mention it."
"A Webmention is a notification that one URL links to another. For example, Alice writes an interesting post on her blog. Bob then writes a response to her post on his own site, linking back to Alice's original post. Bob's publishing software sends a Webmention to Alice notifying that her article was replied to, and Alice's software can show that reply as a comment on the original post."
"Webmention is one of several related specifications being produced by the [[Social Web Working Group]]. Implementers interested in alternative approaches and complimentary protocols should start by reading the overview document [[social-web-protocols]]."