Presents an innovative synthesis of methods used to study problems of equivalence and symmetry.

1. Geometric foundations; 2. Lie groups; 3. Representation theory; 4. Jets and contact transformations; 5. Differential invariants; 6. Symmetries of differential equations; 7. Symmetries of variational problems; 8. Equivalence of coframes; 9. Formulation of equivalence problems; 10. Cartan's equivalence method; 11. Involution; 12. Prolongation of equivalence problems; 13. Differential systems; 14. Frobenius' theorem; 15. The Cartan-Kahler existence theorem.