Think about the last time you walked out of a store without buying anything.
You browsed. You looked. You touched three things and left. The store got nothing.
Except it did.
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It got your attention, your location data, your browsing pattern, possibly your email address, and a place in your memory for the next time you need whatever they sell.
There is an entire category of business built on people who buy nothing. Some of the largest companies in the world are in it.
And understanding how it works is genuinely protective, because most of these systems are designed around your behavior rather than your wallet.
Let us pull it apart.