Pseudonym

A pseudonym (/ˈsuːdənɪm/) or alias (/ˈeɪliəs/) is a fictitious name that a person or group assumes for a particular purpose, which differs from their original or true name (orthonym). This also differs from a new name that entirely or legally replaces an individual's own. The pseudonym identifies one or more persons who have true names (that is, legal identities) but do not publicly disclose them. Most pseudonym holders use pseudonyms because they wish to remain anonymous, but anonymity is difficult to achieve and often fraught with legal issues. True anonymity requires unlinkability, such that an attacker's examination of the pseudonym holder's message provides no new information about the holder's true name.