We used to be identified on the web by our IP address or a Cookie set in our browser.
Nowadays technology has evolved beyond those basic and often unreliable user identification schemes.
Today one third of all websites you visit are likely using an advanced technique, called fingerprinting, to identify your unique browser. This gives advertisers and malicious actors the ability to track you across the web.
Read more: https://pixelprivacy.com/resources/browser-fingerprinting/