You have written a great article, for example on your blog.
Now it's time to spread it over the Internet.
You have a Facebook page with 5 thousands of fans, so you're thinking that advertising your blog article will be an easy task.
You write a perfect Facebook post:

• A capturing image
• An interesting headline
• An attracting short description
• An engaging call to action
• Finally you publish it exactly when your audience is more active.

You then sit down and wait.
After a couple of hours you see that Facebook has shown your post only to 20 of your 5000 fans and may be one of them has clicked LIKE.

Damn! Why?!

I'm not going to write a lot of useless bla bla on how to write an engaging post. This time I speak to you as a software developer, not as a copywriter.
It's not a matter of post quality, the reason must be searched in the Facebook algorithm.

The new post Facebook algorithm

When you write a new post on your Facebook page diary, the following happens

1. Facebook wants to know if your new post can be interesting for its users. 
2. So Facebook tries to display it to a very small percentage of your fans, let's say 1%.
3. If this little set of your fans engages (likes, shares or comments), then Facebook assumes that your post can be interesting... but it's not still sure.
4. So Facebook tries to display your new post to a larger audience, let's say 5% of your fans.
5. If they engage, then a larger audience is reached and so on...

The problem seems that the first small audience has to react, if you want that your post is going to be displayed to a larger audience.
Why it does not happen? Your post is perfect!

Fans quality

The cause is becoming obvious.
If you have an high percentage of followers that do not engage, then statistically the very first group of followers that will see your post, may not engage at all.
This will be interpreted by Facebook as "not interesting post", and your post will become virtually invisible.

This sad thing is not happening only to you, it's happening to everybody!
Do you know why you have so many not engaging followers?
Because most of them are fake.

The fake followers problem

When you create a Facebook page, there are two ways to get fans rapidly: the legal and the illegal way.

• The legal way is to promote your new page using Facebook advertising.
• The "illegal" way is to buy them from agencies that sell them, something like 1000 followers for 10$.

The second way to get followers, will bring you thousands of fake followers. Users that are paid just for clicking LIKEs.
Obviously these users will never engage.

I know what are you thinking. You're thinking that you've never bought followers in the "illegal way". Rather you have used Facebook advertising so your followers are real ones.
Sorry, that's not true.
I'm going to explain you why.

Try to imagine, you are the owner of an agency that sells fake likes.
Your problem is that you do not want that Facebook detects you.
You do not want to be blacklisted.

So, as a fake accounts agency, to confuse Facebook you have not only to click your customers, you have to click everything, promoted accounts too.
This is the reason why also if you have used paid advertising or just public relations, you get with a lot of fake accounts.
You don't have to believe me, take a look at the demographics of your Facebook page fans.

Do they are proportionally spread around the world?
Or strangely, do you have a lot of users from Pakistan, Egypt, Indonesia, etc.?

The solution

Examining the Facebook algorithm, it is now clear that having only 500 real engaging fans it is better than having 500 real fans + 4500 fake ones.
In the first case your new posts will be shown to 500 people, because the majority of the fans will engage.
In the second case your post will be shown to 50 people (the first not engaging 1%). This means that only 5 real fans will see it (10% of 1%).

What can you do to limit your fake fans?

• Scoop REAL fans.
• NEVER buy followers.
• NEVER exchange fans (I like your page if you like mine).
• DELETE fake fans (difficult and annoying task).

By the way there's another solution: stop wasting time with your Facebook page, it's a losing battle.