I am quite new to ad targeting field, and have a question while reading blogs about cookie syncing.
Let's assume User123
has never been to Amazon.com and Facebook.com in her entire life, and the scenario is User123
bought a PS4 on Amazon and then visited Facebook.com and saw a couple ads of Xbox, Nintendo Switch, etc(she visited Amazon first and then Facebook).
When visiting Amazon, Amazon generated a Cookie Amazon123
for User123
and then called Facebook to generate Facebook123
to map to Amazon123
.
Now after leaving Amazon for Facebook, how does FB know that the one who's visiting is actually Facebook123
instead of considering her as a new user and generates Facebook234
? Is it because both Cookies collect other user information (like machine id?) so they can use it to do a matching?
Or if the whole assumption is wrong, what is the correct work flow?