|Look up micro- in Wiktionary, the free dictionary.|
- The size of the influenza virus is about 0.8 to 1.2 micrometres.
- Typical bacteria are 1 to 10 micrometres in diameter. Eukaryotic cells are typically 10 to 100 micrometres in diameter. 
- The metric system was introduced in 1795 with several metric prefixes, of which, however, only six were adopted as SI prefixes by the 11th CGPM conference in 1960, whereas myria (104) as well as double and demi were not adopted. In 1873, micro and mega were recommended by the British Association for the Advancement of Science. The other dates relate to recognition by a resolution of the CGPM.
Symbol encoding in character sets
The official symbol for the SI prefix micro- is a Greek lowercase mu (μ). For reasons stemming from its design, there are two different characters in Unicode, which appear slightly different in some fonts, although most fonts use the same glyph. The micro sign (µ) is encoded in the "Latin-1 Supplement" range identical to ISO/IEC 8859-1 (since 1987), at
U+00B5 (Alt+0181), residing at this codepoint also in DEC MCS (since 1983) and ECMA-94 (since 1985). The Greek letter (μ) is encoded in the Greek range at
U+03BC (Alt+956). According to The Unicode Consortium, the Greek letter character is preferred, but implementations must recognize the micro sign as well.
In circumstances, in which only the Latin alphabet is available, ISO 2955 (1974, 1983), DIN 66030 (Vornorm 1973; 1980, 2002) and BS 6430 (1983) allow the prefix μ to be substituted by the letter u (or even U, if lowercase letters are not available), as, for example, in um for μm, or uF for μF. Similar, capacitor values according to the letter and digit code defined in IEC 60062 (IEC 62) (since 1952), EN 60062, DIN 40825 (1973), BS 1852 (1974), IS 8186 (1976) etc. can be written as 4u7 (or 4U7) instead of 4µ7 if the Greek letter µ is not available.
Other abbreviating conventions
In some health care institutions, house rules deprecate the standard symbol for microgram, "μg", in prescribing or chart recording, because of the risk of misdose via the misreading of poor handwriting. The two alternatives are to abbreviate as "mcg" or to write out "microgram" in full (see also List of abbreviations used in medical prescriptions). But this deprecation, focused on bedside misdose avoidance in contexts where handwriting is often present, does not extend to all health-care contexts and institutions (for example, some clinical laboratories' reports adhere to it, whereas others don't), and in physical sciences academia, "μg" remains the sole official abbreviation.
- International Bureau of Weights and Measures (2006), The International System of Units (SI) (PDF) (8th ed.), ISBN 92-822-2213-6
- Biology by Campbell & Reece tenth edition page 98 Ch. 6 A Tour of the Cell
- Prefixes of the International System of Units, International Bureau of Weights and Measures (page visited on 9 May 2016).
- (Unicode 1.0, 1991)
- Unicode Technical Report #25
- ISO 2955-1974: lnformation processing - Representations of SI and other units for use in systems with limited character sets (1st ed.). 1974.
- "Table 2". ISO 2955-1983: lnformation processing - Representations of SI and other units for use in systems with limited character sets (PDF) (2nd ed.). 1983-05-15. Retrieved 2016-12-14. 
- Vornorm DIN 66030 [Preliminary standard DIN 66030] (in German). January 1973.
- DIN 66030: Darstellungen von Einheitennamen in Systemen mit beschränktem Schriftzeichenvorrat (in German) (1st ed.). 1980.
- "Neue Normen für die Informationsverarbeitung". Computerwoche (in German). 1981-01-09. Archived from the original on 2016-12-14. Retrieved 2016-12-14.
- DIN 66030:2002-05 - Informationstechnik - Darstellung von Einheitennamen in Systemen mit beschränktem Schriftzeichenvorrat [Information technology - Representation of SI and other units in systems with limited character sets] (in German). Beuth Verlag. May 2002. Retrieved 2016-12-14.
- "Commonly Used UCUM Codes for Healthcare Units". HL7 Deutschland e.V. Retrieved 2015-11-21.
- Burtis, Carl A.; Ashwood, Edward R.; Bruns, David E. (2012), Tietz Textbook of Clinical Chemistry and Molecular Diagnostics (5th ed.).