[[File:Droste Cacao Alcalinise blikje, foto4.JPG|thumb|A visual form of recursion known as the [[Droste effect]]. The woman in this image holds an object that contains a smaller image of her holding an identical object, which in turn contains a smaller image of herself holding an identical object, and so forth. 1904 Droste [[hot chocolate|cocoa]] tin, designed by Jan Misset]]
'''Recursion''' occurs when the definition of a concept or process depends on a processsimpler refersor toprevious (invocation(s)version of) itself.<ref>{{Cite book |last=Causey |first=Robert L. |url=https://www.worldcat.org/oclc/62093042 |title=Logic, sets, and recursion |date=2006 |publisher=Jones and Bartlett Publishers |isbn=0-7637-3784-4 |edition=2nd|___location=Sudbury, Mass. |oclc=62093042}}</ref> Recursion is used in a variety of disciplines ranging from [[linguistics]] to [[logic]]. The most common application of recursion is in [[mathematics]] and [[computer science]], where a [[function (mathematics)|function]] being defined is applied within its own definition. While this apparently defines an infinite number of instances (function values), it is often done in such a way that no infinite loop or infinite chain of references can occur, e.g. when each recursive invocation occurs in a somehow simpler setting than its caller.
A process that exhibits recursion is ''recursive''.
