Substitution is the replacement of one thing with another. Specific types include:

In mathematics:

• Substitution rule, in calculus
• The substitution method of solving simultaneous equations
• Substitution property of equality, in mathematics
• Substitution cipher, in cryptography
• Variable substitution method in lambda calculus and mathematical logic

In science and technology:

• Substitution (chemistry), in organic chemistry
• Substitution method, in the testing of optical fiber
• Substitution mutation is synonymous with point mutation in genetics
• Virtual Reality as a substitute for Reality

In economics:

• Import substitution in trade
• Substitute good, in consumer theory

In medicine:

• Substitution therapy for opiates

In Analytic psychology:

• It is a defence mechanism where a person replaces one feeling or emotion for another.

Other uses:

• Chord substitution, in music
• Substitution (law), a legal right to change a judge that may be biased.
• Substitution (theatre), an acting methodology
• Substitutes, in sport
• Substitutionary Covenantal Representation in Biblical Theology

Substitution | Substitution | Substitutie