As mentioned above, the browser knows almost everything you do. It knows what sites you visit, how much time you spend on them, what you look at, what is visible “above the fold” and not occluded by opaque layers, what searches you make, what groups of tabs you open while researching major purchases, etc.
Only the browser, after HTTPS terminates and secure pages are decrypted, has all of your private data needed to analyze user intent. Our auditable open source browser code protects this intent data on the client device. Our server side has no access to this data in the clear, nor does it have decryption keys. We do not run a MitM proxy or VPN service.
We provide signals to the browser to help it make good decisions about what preferences and intent signals to expose to maximize user, publisher and advertiser value. Each ad request is anonymous, and exposes only a small subset of the user’s preferences and intent signals to prevent “fingerprinting” the user by a possibly unique set of tags.