[noobie]

Not really caching but as far as I remember there are HTML Open Graph tags that Facebook checks for in order to fetch the title/description etc.

Check N°3 on this link https://developers.facebook.com/docs/sharing/best-practices

[prawn]

And AFAIK the caching will run for about 30 days unless you clear it manually or through the API. Might be different for major sites.

[jonah]

Yeah, it caches the preview.

As mentioned in that doc, you can use the URL Debugger[1] to see the Open Graph data and even clear the cache.

I cleared the cache for the OP's BBC URL, try sharing it again and see what info you get.

[1] https://developers.facebook.com/tools/debug/

[MiddleEndian]

Good to know. I wonder how those ended up differing.

[jonah]

I assume what you saw was the BBC's title and summary at the time it was first shared (and thus cached) on Facebook. They've since edited it but FB keeps the cached version since the URI hasn't changed.