I use the Internet for personal and business use. In business I participate in USENET discussion groups on technical topics and I sometimes use my real name and company name as part of the signature.
When I use the Internet for a hobby, some of the groups I participate in (some of which argue about politics) I would rather be anonymous to. So I don’t use my real name.
What I didn’t know until recently is that the IP address of the submitter of a USENET post is stored in the message (NNTP) header. So from my business activity, my IP address is associated with my real name. Now when I visit a web site or participate in a newsgroup, someone can get my IP address and search USENET archives looking for the IP address, and trace it back to my real name, company and with the IP address my geographical region and from that my home address and telephone number.