You’re sitting with a friend—just the two of you—and your phones are in your pockets. You might tell him, “I want to buy an air conditioner,” and chat a bit about it. Then you both go home. Later, you open your phone, scroll through Facebook, and suddenly all the posts you see are about air conditioners. Seriously!
You see someone asking in a group: “Guys, I want to buy an air conditioner—what’s the best brand?” And the next post is an air conditioner ad. How is that possible? How did Facebook know I wanted an AC when I only talked about it with my friend?

Has this ever happened to you? Many people lately have noticed this and say it happens a lot.

There are two explanations:

The first explanation (scientific):

When something is on your mind or you want to buy something, you usually search for it on Google—or maybe on shopping sites like Jumia or Souq. Since there’s integration between Google Ads and Facebook Ads, once you enter data about something, artificial intelligence figures out your interests and starts showing you related ads on your feed.

The second explanation (the scary one):

Many people swear they never searched for anything—not on Google or anywhere else. So the only explanation they believe is that Facebook is spying on us, listening to our conversations, picking up words we repeat, turning them into voice data, and then showing ads based on that.

If this second explanation turns out to be true, that would be a disaster. It would mean we’re carrying a device that spies on everything we do daily and fully understands our interests and behavior. Especially after the recent Facebook data leaks—where Facebook sold data of 50 million users for Donald Trump’s presidential campaign—people have started to doubt and say: maybe spying really is happening.

In any case, whenever you talk about something private, make sure your Wi-Fi is turned off, and try not to put your entire personal life on Facebook.