+A **function** is a precise rule, defining how each [Input](/wiki/input) corresponds to exactly one [Output](/wiki/output). This fundamental concept describes a unique relationship, essential in [Mathematics](/wiki/mathematics) and across many branches of [Science](/wiki/science).
+## See also
+- [Mapping](/wiki/mapping)
+- [Relation](/wiki/relation)
+- [Algorithm](/wiki/algorithm)
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