What does the Publication of Private Facts tag mean? [1]

This tag describes situations where the sending/suing party asserts a claim based on the receiving/defending party's publication of private facts about his/per personal life. These types of claims are sometimes labeled "invasion of privacy" claims by a suing/sending party. Note that there are other species of "invasion of privacy" torts as well -- "false light" and "intrusion" -- so try to determine which type is implicated in a particular situation.