Finite symmetry groups such as the Mathieu groups are used in <answer>coding theory</answer>, which is in turn applied in error correction of transmitted data, and in CD players. Another application is differential Galois theory, which characterizes functions having antiderivatives of a prescribed form, giving group-theoretic criteria for when solutions of certain differential equations are well-behaved.u[›] Geometric properties that remain stable under group actions are investigated in (geometric) invariant theory.
What is used for error correction of transferred data?
coding theory