Prototypes or prototypical instances combine the most representative attributes of a category. They are the best examples among the members of a category and serve as benchmarks against which the surrounding "poorer" instances are categorized (see Prototype (linguistics)).
"Prototype" can also refer to a test machine, circuit or program which is designed for demonstration purposes. It also enables the testing of the new product's design before the product is put into production. Problems or deficencies in the product's design can be discovered and corrected. When the prototype is sufficiently refined and meets the functionality, robustness, manufacturability and other design goals, the product is ready for production. Often such prototypes are built using techniques different than techniques for mass production -- see prototyping.
See also: Categorization, Semantics
Computer science
In computer science, a prototype is the declaration of a subroutine. However, in object-oriented programming, a prototype is also known as the object-class combination that prototype-based programming is based on.
Model railroads
Among model railroad enthusiasts, at least in North America, actual railroads are commonly spoken of as "prototypes".
Automobile racing
Cars from the premier tier of international sports car racing are informally called 'Prototypes'. Unlike GT cars, which are road-legal cars modified for racing, Prototypes are designed purely for track use. The overall winners of multi-class events like Le Mans are usually Prototypes. Examples of Prototypes include the Porsche 917 and Audi R8.