Abstract: The dynamical mean field theory (DMFT) is a very useful tool in studying strongly correlated materials and has been applied to many lattice models with strong Coulomb interactions since its birth in the early 90's. In this talk, the DMFT is explained in detail and various quantum impurity solvers for the DMFT are introduced. As an application of the DMFT, the so-called BCS+U model is considered. In its specific form, the BCS+U model resembles the conventional BCS Hamiltonian, but the pairing amplitude possesses a d-wave symmetry. It is shown that in combination with the DMFT the BCS+U model can shed some light on the occurrence of pairing in high-temperature superconductors.