No doubt you've come across this post, or one like it, in your Facebook feed at some stage.
They're not hard to find - there are many examples of the same post being shared over and over on the platform if you search for a section of the text.
The engagement stats on some of those posts are frightening, because anyone who's taken any time to read about Facebook's News Feed algorithm and how it works would know that this is not true. But the way in which the algorithm does work could lead people to quite believe that it might be plausible.
But no - clarifying this specific viral post type, Facebook has provided a new explanation which debunks the myth:
"Though multiple publications have debunked this meme, it continues to persist. So, to clear things up: No, Facebook does not set a limit on the number of people whose posts are shown in your News Feed."
In further explanation Facebook says that because the posts which appear in your News Feed are ranked in the order that Facebook's system believe you’ll be most interested in seeing them, it is possible that you’ll end up seeing content from a similar list of people at the top of your News Feed - which may help fuel the “25 friends” theory. But that's not a deliberate or defined process - "if you scroll down, you’re likely to see posts from an even wider group of people."
This is similar to the explanation Instagram recently provided over its own '7% post reach' viral myth - in that post, Instagram notes that what you're shown in your feed is determined by who you follow, the profiles you engage with, the time something was posted, etc.
As such, theoretically, that could mean that your reach would end up appearing to be limited to a small subset of the profiles you follow - but it's not a system restriction, Instagram hasn't come up with an arbitrary number at which to stop post reach. The algorithm merely shows you what you're more likely to engage with - so if you like and comment on posts from a smaller group of close friends and relatives more than you do everyone else you're connected to, then more of their future posts will show up atop your feed.
It's not a system limitation, it's your own friendship circles that limit what you're shown.
The same is true for the idea that if you comment on a post from a person, that it will somehow “unblock” them and you'll see their content in your feed again. That's not true, because they were never blocked to begin with, but if you do comment on their post, they are more likely to show up in your stream. You would need to engage with their posts regularly for this to have any lasting effect - but that, once again, can help add fuel to the notion that Facebook is deliberately limiting post reach.
In order to keep growing, and keep investors happy, Facebook needs to show growth, and not just in terms of audience size, but in usage also. To do that, they need to keep people engaging - so it simply doesn't make any sense for Facebook to be deliberately restricting post reach from profiles which you might otherwise engage with.
What you're shown is based on your interaction history. If you do want to have more control over what you see in your feed, Facebook notes that there are various options to assist:
"...we’ve built, and are continuing to build, new controls so that people can directly tell us what they want to prioritize, take a break from or get rid of. If you want to make sure you see everything from a certain person, you can use the See First feature to put that person’s posts at the top of your Feed. If you’ve heard too much from someone, you can Unfollow them. If you just want to take a break from someone, the Snooze feature removes them from your News Feed for 30 days."
The News Feed can be tricky to use to advantage, particularly for brands, because it's reliant on businesses creating engaging content, which users feel compelled to interact with, to 'Like' and to share. That's not necessarily easy to do, especially while also staying 'on brand' and focused on your offerings, but the News Feed algorithm itself, fundamentally, is not incredibly difficult to understand. The more people actively engage, the more likely they'll see more similar content in their feed.
The same principle applies to personal connections, though Facebook actually wants users engaging with other people over brand and Business Page interaction.
There are always variants of this type of tinfoil hat theory circulating through the Facebook graph, but they're not true, and there are plenty of resources available to read up on how the system actually works to assist.