How Whatsapp is making billions of dollars ?
Buying Whatsapp for $19 billion was the smartest move Facebook made. I'll keep it short.
It's all about gathering and selling data, majority of the Facebook users do not have a clue how they are the product.
Most of the services which are 'free' makes users their product and make money out of it. Making money by just gathering some personal information about you and selling it. If one would read the privacy agreement of those applications (which we hardly do) they would be surprised to see what they are accepting before they use those 'free' services. In short, you agree to trade your personal details, likes, relationships etc for using those 'free services' which are not actually free.
Believe it or not, here's the 'behind the scenes' how their algorithm works?
They collect your data, understand your likes, and sell stuff to you through their advertisers.
Don't hesitate trying it.
Who's the buyer?
Let's say you're on a limited budget and you open up a business, you want only the people who are interested in your services to know about your business when you advertise it online, there's no way you can get information about individuals who are interested in your services. But Facebook is known for knowing one better then his/her spouse. So you can go to Facebook open up a page ask them to advertise your campaign only to those people who are actually interested in it. Saving you some money and making Facebook a 100% profit. By selling something they got it for free.
This is how it works. And now you know why Mark Zuckerberg's net worth is doubling almost every 2 years.