For questions about type theory, including normalization, dependent types, identity types, inductive types, universe types, functional programming languages, proofs as programs in simply-typed lambda-calculi, Martin-Löf's intuitionistic type theory or related.Consider using one of the following tags: (lambda-calculus), (logic), (constructive-mathematics),(homotopy-type-theory) if related.

The field of type theory relates fundamental concepts in logic, computer science, mathematics and philosophy. It deals with a class of formal systems where every term has a type and operations restricted to terms of some types.

A more detailed explanation can be found in Stanford Encyclopedia of Philosophy.