A pseudonym or alias is a name that a person or group assumes for a particular purpose, which can differ from their original or true name (orthonym).
Pseudonyms include stage names and user names (both called screen names), ring names, pen names, nicknames, aliases, superhero or villain identities and code names, gamer identifications, and regnal names of emperors, popes, and other monarchs. Historically, they have often taken the form of anagrams, Graecisms, and Latinisations, although there are many other methods of choosing a pseudonym.
Pseudonyms should not be confused with new names that replace old ones and become the individual’s full-time name. Pseudonyms are “part-time” names, used only in certain contexts – usually adopted to hide an individual’s real identity, as with writers’ pen names, graffiti artists’ tags, resistance fighters’ or terrorists’ noms de guerre, and computer hackers’ handles. Actors, musicians, and other performers sometimes use stage names, for example, to mask their ethnic backgrounds.
In some cases, pseudonyms are adopted because they are part of a cultural or organisational tradition: for example devotional names used by members of some religious institutes, and “cadre names” used by Communist party leaders such as Trotsky and Lenin.
A pseudonym may also be used for personal reasons: for example, an individual may prefer to be called or known by a name that differs from their given or legal name, but is not ready to take the numerous steps to get their name legally changed; or an individual may simply feel that the context and content of an exchange offer no reason, legal or otherwise, to provide their given or legal name.