Multigrid techniques are used in most commercial computational fluid dynamics codes where large numbers of unknowns are common. The techniques are used to accelerate convergence of basic iterative methods using multiple grid levels. In this course we apply basic multigrid techniques to one- and two-dimensional elliptic problems discretized using a finite-difference method. The approach may be extended to the finite-volume and other methods, or may be applied to general sparse linear systems of the form Ax=b. The one- and two-dimensional codes are written in Fortran90 and source codes available for download. Prospective students should be familiar with basic numerical methods and be proficient in a scientific programming language.