What is ad profiling?
Ad profiling builds a detailed portrait of each internet user from their searches, trips, purchases and emails, then sells advertisers the ability to target it. It is the business model of free services: you do not pay with money, you pay with your profile. The topic continues in chapter 3 of my book, Vivre sans Google.
Information verified on July 13, 2026
An identikit portrait of you, drawn without you ever posing for the picture. Every search, every trip, every email received adds a line: probable age, estimated income, purchase plans, health worries. The ad platform sells that portrait to advertisers, who pay to reach exactly your profile at the right moment.
That is the business model of free. You pay for neither the search engine nor the mailbox: advertisers pay in your place, in exchange for your attention and your portrait. Nothing illegal there. But in that market, you are not the customer, you are what is being sold.
What makes Google unique is the crossing of sources. A single site only knows a fragment of your life. Google connects your searches, your movements, your videos and your emails to the same account. Who else can match what you search for at night with the place where you sleep?
Where it plays out: chapter 3 of the book takes this machinery apart piece by piece, the Search engines category presents engines that draw no portrait, and the leaving Gmail and deleting your Google account guides cut off the main sources.
This topic is chapter 3 of my book
It answers these questions, among others:
- how do you change the default engine everywhere, phone included, without missing a device?
- what about image, shopping, translation and academic searches?
- and what do you offer a loved one who refuses to change their search habits?
Forthcoming 22/10/2026 from Éditions Eyrolles
Where do you stand?
24 questions to measure how much you depend on Google services. Free, no sign-up.
Tech jargon, translated
Every week in The Spark, I break down one tech story through the privacy lens. And what you can do about it, concretely.
Join 400+ readers. Unsubscribe in one click. Your data will never be shared.