Orienting visual attention is of fundamental importance when viewing a visual scene. One of the areas thought to play a role in the guidance of this process is the posterior parietal cortex. In this review, we will describe the way the lateral intraparietal area (LIP) of the posterior parietal cortex acts as a priority map to help guide the allocation of covert attention and eye movements (overt attention). We will explain the concept of a priority map and then show that LIP activity is biased by both bottom-up stimulus-driven factors and top-down cognitive influences, and that this activity can be used to predict the locus of covert attention and initial saccadic latencies in simple visual search tasks. We will then describe evidence for how this system acts during covert visual search and how its activity could be used to optimize overt visual search performance.