Traditionally, Patterson search methods were the only methods available for solving molecular structures from powder diffraction data. Nowadays, they still constitute, specially for molecules with fixed geometry, an alternative to real-space structure determination methods. In the future, it is probable that the solutions found by Patterson search methods will be used as starting point for further real-space refinement, due to their easy of computation. In this way the potentials of Patterson search and real-space methods could be combined in an effective manner.
The foundations of Patterson search methods (rotation and translation functions) will be briefly described. This basic knowledge is necessary for estimating both the control parameters of  Patterson search programs as well as  the optimum  size and form of search models. Since the application of Patterson search methods to powder data has limitations arising from the unavoidable peak overlap, these problems will also be commented. To complete this description a short introduction to the direct methods sum function will be given in order to illustrate the parallelism between Patterson search methods and this specific direct methods strategy.
Finally, some examples on the application of  Patterson search methods to real problems will be demonstrated.