architect gains insight. Metrology In the science and practice of metrology, a prototype is a human-made object that is used as the standard of measurement of some physical quantity to base all measurement of that physical quantity against. Sometimes this standard object is called an artifact. In the International System of Units (SI), there remains no prototype standard since May 20, 2019. Before that date, the last prototype used was the international prototype of the kilogram, a solid platinum-iridium cylinder kept at the Bureau International des Poids et Mesures (International Bureau of Weights and Measures) in Sèvres France (a suburb of Paris) that by definition was the mass of exactly one kilogram. Copies of this prototype are fashioned and issued to many nations to represent the national standard of the kilogram and are periodically compared to the Paris prototype. Now the kilogram is redefined in such a way that the Planck constant is prescribed a value of exactly Until 1960, the meter was defined by a platinum-iridium prototype bar with two marks on it (that were, by definition, spaced apart by one meter), the international prototype of the metre, and in 1983 the meter was redefined to be the distance in free space covered by light in 1/299,792,458 of a second (thus defining the speed of light to be 299,792,458 meters per second). Natural sciences In many sciences, from pathology to taxonomy, prototype refers to a disease, species, etc. which sets a good example for the whole category. In biology, prototype is the ancestral or primitive form of a species or other group; an archetype. For example, the Senegal bichir is regarded as the prototypes of its genus, Polypterus. See also 3D printing Clay modeling Minimum viable product Rapid prototyping Test article (disambiguation) References Industrial design Product development Prototype