Every time you browse the web, small pieces of data called 'cookies' are stored on your device. While some of these are necessary for websites to function properly, others exist solely to track your behavior.
First-Party vs. Third-Party Cookies
First-party cookies are created by the exact website you are visiting. They remember your login details or items in your shopping cart. They are generally helpful and safe.
Third-party cookies, however, are created by domains other than the one you are visiting directly, hence the name 'third-party'. They are usually linked to advertisements, widgets, or social media buttons embedded on the page.
How Do They Track You?
Imagine you visit a clothing store website, and they have an invisible Facebook tracking pixel (a tiny image) that relies on third-party cookies. When you leave the clothing site and visit a news website that also uses Facebook's ad network, Facebook recognizes your cookie.
Because of this, they can follow you across the internet, building a massive profile of your interests, which is why you suddenly see ads for those exact shoes you just looked at.
The Future of Third-Party Cookies
Privacy norms are shifting. Browsers like Safari and Firefox block third-party cookies by default, and Google Chrome is slowly phasing them out. However, advertising companies are already developing new tracking methods like 'Browser Fingerprinting' to bypass these restrictions.
It's more important than ever to understand what data websites collect by reading their privacy policies.