Feeds on BBS Home page.

I actually don't remember when the Feeds was introduced in BBS, So I really don't get how it works.

Today I see that many posts From Gamtech and Sativa community on top of the feeds. Posts from other community are displayed but you'll find them after scrolling down little bit. 

So my question is how the feeds page work? Does it work based on some BBS algorithm system or is it updated manually by bbs team?

If it's Algorithm based then, does it select total random posts or the posts with high level of interaction etc....

If someone would explain it to me or direct me to a post where an explanation is given, I'd really appreciate it. 

Thank you.