Are IP addresses used for tracking / advertising?

Question

Many advertisers use tracking cookies or user-accounts (e.g. being logged into facebook or google while web browsing) to create relevant targeted advertising.

However, what about IP addresses alone? For people that share an IP address (e.g. family home router, or a business), is it possible that they will receive advertising that has been directed to them because of what someone else on that IP has been doing (on a different computer)?

From a technical standpoint, this can be easily done, but

• does it make sense from an advertising point of view?
• Is it a privacy issue if you can guess what other people from your IP address are searching for based on ads you receive?
• Is this something that is already occurs commonly in 2015?

Answer 1

For a detailed user profiling IP addresses by its own are not exact enough because in today's world of mobile devices the IP address of the same user changes too often and also multiple users have the same public IP address.

But IP addresses are used to get the approximate location of the user and thus do location aware advertisements. Or they can be associated with some organization (company, university) and thus add additional information to the user profile. Together with a known profile of the company targeted ads can be delivered to specific business areas (IT security, health care, education...) or single companies. Such detailed profiling is actually offered by the advertisement companies.

Interestingly the same targeting techniques are also used to deliver malware in targeted attacks against some company. And increasingly the ad-networks are used to deliver this malware (malvertisement).