Prototype
Prototypes or prototypical instances combine the most representative attributes of a category. It is the best exemplar among the members of a category and serves as a cognitive reference point with respect to which the surrounding "poorer" instances are categorized.A 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 products design can be discovered and corrected. When the prototype is sufficiently refined and meets the functionality, robustness, manufacturabilty and other design goals, the product is ready for production.
See also: Categorization, Semantics
Computer Science
In computer science, a prototype is the object-class combination that prototype-based programming is based on. Rarely, the declaration of a subroutine is also described as a prototype.
Model Railroads
Among model railroad enthusiasts, at least in North America, actual railroadss are commonly spoken of as "prototypes".