Policy based routing (or PBR) is a process that has the router put packets through a route map before routing them. This may be a good way of sending packets to a particular path for protocol security routes, for instance, instead of using the default shortest path algorithm.
To use PBR, just identify the route map that you want to use for policy-based routing and then create the route map on the interface.
Here is the syntax to define the route map for Policy-based routing:
routera(config)# route-map map-tag [permit | deny] [sequence-number]
For more step-by-step how-to information on configuring and using PBR, see my full article: How to use the Cisco IOS Policy-Based Routing Features