Substitution

In general, substitution is the replacement of one thing with another. There are many specific examples:

In organic chemistry, a reaction where one functional group takes the place of another. A major type of substitution is nucleophilic substitution.
The substitution cipher in cryptography.
The substitution rule in calculus.
Import substitution in trade.
Substitute good in consumer theory.
The substitution method in the testing of optical fiber.
The substitution property of equality in mathematics.

This is a disambiguation page; that is, one that points to other pages that might otherwise have the same name. If you followed a link here, you might want to go back and fix that link to point to the appropriate specific page.