In disciplines such as logic, metalogic, typography, and computer programming, the type–token distinction is a distinction that separates a descriptive concept from objects that instantiate the concept, seen as particular instances of it. For example, the sentence “the bicycle is in the garage” refers to a token of the type named “bicycle”, while the sentence “the bicycle is becoming more popular” refers to the type. This distinction in computer programming between classes and objects is similar, though in this context, “class” may refer to a set of objects (with class-level attribute or operations) rather than a description of an object in the set. The words type, concept, property, quality, feature and attribute are all used in describing things. Some verbs fit some of these words better than others. E.g. You might say a rose bush is a plant that instantiates the type(s), or embodies the concept(s), or exhibits the properties, or possesses the qualities, features or attributes “thorny”, “flowering” and “bushy”. The term “property” is used ambiguously to mean property type (height in feet) and/or property instance (1.74). The term “concept” is probably used more often for the property type (height in feet) than the property instance. Types like “thorny” are often understood ontologically as concepts. Types exist in descriptions of objects, but not as tangible physical objects. A type may have many tokens. However, types are not directly producible as tokens are. One can show someone a particular bicycle, but cannot show someone the type “bicycle”, as in “the bicycle is popular.” It is often presumed that tokens exist in space and time as concrete physical objects. But tokens of the types “thought”, “tennis match”, “government” and “act of kindness” don’t fit this presumption. Clarity requires us to distinguish between abstract “types” and the “tokens” or things that embody or exemplify types. If we hear that two people “have the same car”, we may conclude that they have the same type of car (e.g. the same make and model), or the same particular token of the car (e.g. they share a single vehicle). The distinction is useful in other ways, during discussion of language.
