Jon

Webmentions are a simple protocol for notifying a website when another website links to it². They can be used to display comments, likes, replies, or other types of interactions on the linked page. Webmentions are based on HTTP requests and do not require any specific data format or vocabulary².

ActivityPub is a more complex protocol for creating, updating, and deleting content, as well as delivering notifications and content between different servers³. It can be used to support various types of social network activities, such as following, posting, sharing, or blocking. ActivityPub is based on the ActivityStreams 2.0 data format and vocabulary, and it uses JSON-LD for representing objects and activities³.

Webmentions and ActivityPub can be used together or separately, depending on the needs and preferences of the website owners and users. Some websites use Webmentions to receive interactions from other websites, while using ActivityPub to send interactions to other servers. Some websites use ActivityPub to federate with other platforms that support the same protocol, while using Webmentions to communicate with platforms that do not. Some websites use both protocols to maximize their reach and engagement⁴.

There are also some efforts to bridge the gap between Webmentions and ActivityPub, such as using tools like Bridgy Fed or LDN to convert notifications from one protocol to another⁵. These tools can help increase the compatibility and interoperability between different social web protocols. However, they may also introduce some challenges or limitations, such as data loss, duplication, or inconsistency⁵.