I just enabled the Webmention plugin on my blog. Webmention is a descendant of Pingback. It’s a linkback  protocol that notifies other sites that they were linked from this site. Linked sites could use that information to update a “favourite” or a “clap” counter. Or they could just list the links as part of decentralised, distributed discussions. Webmention is a W3C Recommendation. And it’s a part of the POSSE movement. Find out on IndieWeb who else uses Webmention.