How to get the contact details of website visitors through cookies?

Question

HTTP Cookies

Recently, a familiar marketer told me that you can somehow pull out the contact details of your site visitors using cookies. Is it true? If yes, then tell me where to read, how to write a script, etc.? The network did not manage to google the info.

Answer 1

You were a few years late and it worked not through cookies, but through the VK / classmates API.
"Through cookies" is an excuse for not groping at all.