Editing Fin (section)

{{Short description|Thin component or appendage attached to a larger body or structure}}
{{about|the term in aerodynamics|other uses}}
[[File:Trailing edge NACA 0012.svg|thumb|300px|{{center|Fins typically function as [[foil (fluid mechanics)|foils]] that provide lift or thrust, or provide the ability to steer or stabilize motion in water or air.}}]]

A '''fin''' is a thin component or appendage attached to a larger body or structure.<ref>{{cite book |title=A Dictionary of Aviation |first=David W. |last=Wragg |isbn=9780850451634 |edition=first |publisher=Osprey |year=1973 |page=131}}</ref> Fins typically function as [[foil (fluid mechanics)|foils]] that produce [[lift (force)|lift]] or [[thrust]], or provide the ability to steer or stabilize motion while traveling in water, air, or other [[fluids]]. Fins are also used to [[Fin (extended surface)|increase surface areas for heat transfer purposes]], or simply as ornamentation.<ref>[https://web.archive.org/web/20121029054614/http://oxforddictionaries.com/definition/american_english/fin Fin] ''Oxford dictionary''. Retrieved 24 November 2012.</ref><ref>[http://www.merriam-webster.com/dictionary/fin Fin] {{Webarchive|url=https://web.archive.org/web/20201126080311/https://www.merriam-webster.com/dictionary/fin |date=2020-11-26 }} ''Merriam-Webster dictionary''. Retrieved 24 November 2012.</ref>

Fins first evolved on [[fish]] as a means of locomotion. [[Fish fin]]s are used to generate [[thrust]] and control the subsequent motion. Fish and other aquatic animals, such as [[cetaceans]], actively propel and steer themselves with [[pectoral fin|pectoral]] and [[Caudal fin|tail fins]]. As they swim, they use other fins, such as [[dorsal fin|dorsal]] and [[anal fin]]s, to achieve stability and refine their maneuvering.<ref name=Sfakiotakis /><ref name=Helfman>Helfman G, Collette BB, Facey DE and Bowen BW (2009) [http://limnology.wisc.edu/courses/zoo510/2009/helfman_ch8.pdf "Functional morphology of locomotion and feeding"] {{webarchive|url=https://web.archive.org/web/20150602082907/http://limnology.wisc.edu/courses/zoo510/2009/helfman_ch8.pdf |date=2015-06-02 }} Chapter 8, pp. 101–116. In:''The Diversity of Fishes: Biology'', John Wiley & Sons. {{ISBN|9781444311907}}.</ref>

The fins on the tails of cetaceans, [[ichthyosaurs]], [[metriorhynchids]], [[mosasaurs]] and [[plesiosaurs]] are called '''flukes'''.