There are many different approaches to starting a genomic analysis. These include literature searching, searching databases for gene names and other genomic features, performing sequence comparisons, or using map data to find gene information by position relative to other landmarks. The NCBI Map Viewer has been developed to facilitate this latter approach.

The purpose of this chapter is to provide a foundation for gaining maximum benefit from using the Map Viewer and related resources at NCBI. It is important to note that in this document, the term "map" refers to a position of a particular type of object in a particular coordinate system. This means, for example, that there is not one sequence map but a set of maps in sequence coordinates. Readers interested in precisely how sequence-based maps are annotated and assembled should refer to Chapter 14.