Cross-posting is the social media practice of syndicating or placing the same content, possibly slightly modified, on numerous different websites.

For example, an organisation will have a blog post on its own website that it copies to websites of other places with similar objectives or to silos such as LinkedIn where a larger audience may see it. This is essentially POSSE without the name, practised by people who don’t know that they are being a little bit indieweb in doing so. It is often accompanied by an apology, such as “Apologies for cross-posting”. (The apologies are ostensibly meant for people who are following them on multiple platforms and thus seeing the same message multiple times.)

Cross Posting, IndieWeb, https://indieweb.org/cross-posting