http://protonmailrmez3lotccipshtkleegetolb73fuirgj7r4o4vfu7ozyd.onion/blog/browser-device-fingerprinting
This is because the more they know about you, the better they can target ads at you. They are therefore very keen on tracking your activities on the internet to build up a detailed model of your likes, dislikes, hobbies, and more, based on your web browsing history.