Wikipedia:Divulging personal details
How much personal information should a biography divulge? What if the subject of the biography would rather not have the information published? What if publication of the information might lead to real harm? When is it appropriate to edit such information out of an article? When should it be edited out of the article? When should it be hidden from all but administrators by use of the revision deletion feature?
This is a recurring question. The most common type of damaging personal information revealed is the real identity behind a pseudonym (though home addresses, phone numbers, even Social Security numbers have been posted as well). Revealing this information may threaten the subject with harassment, loss of employment, legal action, or even physical harm.
A broad policy of excluding information upon any request by the biography's subject is not viable. Unfavorable information, for example about scandals or negative opinions held by others, would quickly disappear from numerous articles, offending the obligations of NPOV, accuracy, and completeness. Instead, the question of what to include and what to leave out usually turns on verifiability.
Facts should be verifiable from a reliable source. If a reliable source (say, a national newspaper) has published a piece of information, including that fact in an article will probably cause no further harm. Anyone seriously interested in discovering the information could have done so without reading the Wikipedia article. (Wikipedia's high PageRank and numerous mirrors, however, can make previously little-known information much more public than it was before.) Facts that are not verifiable from a reliable source should probably be left out. This would include gossip from Usenet or other online forums, personal websites, etc.
Information that is demonstrably dangerous to others has, in the past, been removed from edit histories without objection.