Your personal information is Facebook’s currency. It’s bought and sold every day.
When advertisers want to target a specific group of customers who, for example, are a particular age and have a certain political affiliation or interest, Facebook makes that possible. The stuff you share and the inferences Facebook makes about you are packaged together with similar people’s data, stripped of names and sold to companies. That allows businesses to put ads in front of people they’re certain they can influence.
On Facebook, you are the product. Advertisers are the customer.
Facebook’s not alone. Most advertiser-supported networks sell some of your information to third parties. Google, Microsoft, Yahoo, AOL, Amazon, Twitter and Yelp do the same.
Giving up our privacy is the price we pay for getting to use Facebook for free. Most of the time, that tradeoff works: People take advantage of free services by posting, searching and sharing. Most companies that collect our data use it for legitimate purposes and within the bounds that companies like Facebook permit.
for example a political campaign may want to reach Woman age 24 to 35, so they buy that audience and you see the ad.
its really that simple. It’s been going on since Facebook had its first advertising sale and it’s nothjng to worry about, everyone is already doing it, stores, credit cards, colleges and pretty much every place you buy from online.