+A **substrate** is an underlying substance or [surface](/wiki/surface) upon which another entity exists, acts, or grows. In chemistry, it often refers to the [reactant](/wiki/reactant) upon which an enzyme or catalyst acts to facilitate a reaction.
+## See also
+- [Growth Medium](/wiki/growth-medium)
+- [Enzyme](/wiki/enzyme)
+- [Catalyst](/wiki/catalyst)
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