"I.P. addresses are digital tags that can identify a specific computer" That's misleading. An IP address can't always uniquely identify the client computer.

"I.P. addresses are digital tags that can identify a specific computer" That's misleading. An IP address can't always uniquely identify the client computer. For starters, people can use proxies or anonymizers. "Yahoo will also ... strip out any personally identifiable information, like a name, phone number, address or Social Security number" Who is giving their SSN to Yahoo, and why??