Within geographic information science, scale has several meanings. To the general public, geographic scale may be most frequently understood in the sense of map scale, shown as a scale bar on a map. More generally, scale is the relationship between an abstract respresentation of something and the real thing, whether this is planet earth or a building plan. From a geographic information science perspective, the most important aspect of scale is how it affects the analysis of spatial data. This entry therefore starts with a definition of map scale, moves on to a discussion of a more generic use of the notion of scale and how it affects geographic analysis, and ends with an overview of one theoretical approach to understanding phenomena over multiple scales.