The word standard has several meanings:
Classically, standard referred to a flag or banner; especially, a national or other ensign carried into battle; thus "standard bearer" indicates the one who bears, or carries, the standard. The modern primary meaning evolved through symbolism: "a quality or measure which is established by authority, custom, or general consent". In the phrase "light standard" it retains the older meaning of a vertical support.
In technical use, a standard is a concrete example of an item or a specification against which all others may be measured. For example, there are "primary standards" for length, mass (see Kilogram standard), and other units of measure, kept by laboratories and standards organizations. Officially certified measuring instruments must be checked for accuracy using such standards (or secondary standards made from the primary).
In analytical chemistry a standard is a preparation containing a known concentration of a specified substance. A simple standard may be a dilute solution of the substance; this serves as a reference to calibrate equipment used to measure a sample's composition in terms of compounds or elements. For accuracy, real samples are bracketed by known standards, that is, standards are analyzed that contain concentrations of the analyte that are less than and greater than the real sample's concentration.
There are also certified reference material s available which contain independently verified concentrations of elements available in different matrices (a matrix is bulk material of the sample, for example blood).
- Ideal standard
- International standard
- Jazz standard in music
- Open standard or its antonym, proprietary (e.g., proprietary software)
- Standards organizations
- Building code
- Standard transmission