Figure 1.

Three examples of standards in different domains. (a) The phosphodiester bond (dashed circle), a standard interface linking the nucleotide building blocks of RNA and DNA, such as the nucleotides containing adenine (‘A’) and guanine (‘G’) of this RNA example. (b) An ancestral Pueblo cooking pot. The exterior texture was created by combining the raw materials of pottery with techniques from basket weaving. ‘Corrugated’ vessels like this improve cooking control relative to older, plain-surfaced vessels. Courtesy of Crow Canyon Archaeological Center. (c) A standard NOR (‘not OR’) logic gate comprised four transistors. Millions of identical copies of this and a few other gate types are interconnected on a single integrated circuit to perform logical and arithmetic functions.