Privacy Sandbox is made to eliminate the ability of individual, 1:1 tracking and identification of users, also called “fingerprinting”.
As of today, online advertising is mostly reliant on so called (third-party) browser cookies. These are basically simple short text files containing an identifier and an expiry date, that are created when you visit a website, and then stored on your device for a specified time. Advertising cookies usually are stored for a month.
There are two main types of cookies, first and third party cookies. First party ones are created directly by the website you are visiting, and these enable essential functions for the page to remember your login data, or items added to your cart.
Third-party cookies are created by other services, not by the visited domain itself. These play a crucial part in online analytics and advertising, enabling retargeting, cross site-conversion tracking, or profiling. An example:
First-Party Cookie: A user visits www.mito.hu and a cookie is created by www.mito.hu to store some settings made by the user
Third-Party Cookie: A user visits www.mito.hu and a cookie is created by ad.doubleclick.net or facebook.com, with the purpose of assigning the user to audience pools that later retarget them with personalized messages.
Each advertising service has fancy names for their trackers, such as Google’s Floodlight, Linkedin’s insight tag or Facebook’s pixel. Don’t be fooled: they are all simply third-party trackers.