[manigandham]

Advertisers don't. It's all anonymized and usually as a big bucket of either demographics, interests or matched to a customer list of some sort. Honestly targeting an individual person online is very hard and expensive - at that point you probably have their name so you can just get their address and send them some mail instead.

The major companies like Google, Facebook, LinkedIn and other sites with logins will have more personal info because people provide it willingly, but they also keep this as valuable 1st party data since it's their edge in the ad business. Advertisers don't get access to it but can target against it if they advertiser on that specific platform.