World Theory


define: avatar, character, persona...

Users of virtual worlds are usually represented in the world in terms of a character and the avatar of that character. Here are my definitions...

(Please note that these definitions are preliminary and are likely to change.)

An agent is an entity in the world that is perceived as being autonomous and which is viewed as being capable of causing actions to take place.
A character in a virtual world is an identifiable entity that is also an agent. The character has a collection of associated traits. These traits includes data represented in a simulation as well as information about the characters personality, the latter doesn't have to be represented in the simulation. A character is often given a description which will make a human being think of it as a single individual, but that is not required.
A persona is a character which a user has established in a virtual world and which the user identifies strongly with. The persona is used as a mask in the virtual world allowing the user to take on new roles and a divergent personality which doesn't match how the user is perceived by others in the real world.
An avatar is the collection of signs which signifies a character's presence in a virtual world. The avatar may be represented as a combination of icons, textual names, graphical figures, sounds, smells or any identifying set of signs that can be mediated through the system.
A handle is a discriminating identifier which can be used to address an entity in the world. A character often has a unique name as it's handle.


The terms defined here are often confusingly used to denote incompatible phenomena by different authors. It is for instance not unusual for users to confuse the term avatar and character. Some authors use the terms persona and character as synonyms, which is reasonable, but wasteful... I have chosen to distinguish those terms by using persona to refer to a subset of characters.

Related terms

One might want to distinguish between characters controlled by a computer and characters controlled by a user.. This distinction is usually accomplished by referring to the former as a Non-Player Characer or NPC for short, and the latter as Player Characters or PC for short. This distinction is often used when the computer controls characters that are roughly similar to those controlled by players. The term mob or mobile, a computer-controlled movable object, can also be used to refer to NPCs and similar computer-controlled entities.

Users often use the term toon to refer to either their avatar or their character, or both.