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Numerous types of geographic information management technologies are currently available on the Web, ranging from simple tools for viewing maps to more complex systems such as Geographic Information Systems (GIS). The term GIS is commonly applied to all automated mapping. However, it specifically describes a system of computer hardware, software, and geographically referenced data, designed to capture, store, edit, display, and plot spatial information.
Geographic Information Systems (GIS) merge the graphic features of a map with its associated data, and because of this, in-depth analyses of geographic relationships are possible. GIS is often defined by its method of storing data and features in layers, allowing users to overlay various types of information to view simultaneously. The number of automated mapping tools that share some, but not all, of these capabilities is increasing, and more and more information is being made available using geographic technologies.
Understanding the capabilities, benefits, and limitations of these tools can greatly enhance reference service in both traditional and virtual environments. In fact, familiarity with some of the geographical resources on the Web can answer many common reference inquiries. For example:
Maps effectively illustrate data. For instance, if a researcher is seeking the latest population numbers for a particular neighborhood, a map of that area in the context of the entire city with associated statistics is more helpful. Similarly, a map of Superfund locales or toxic release sites can be more effective than a listing, as a visual display of the highest concentrations of harvested croplands or forest cover types is preferable to a description.
Maps act as alternative finding aids, particularly when features are more easily identified graphically. GIS technologies commonly have clickable maps that link locational information to pertinent data. For instance, a prospective homebuyer can research what houses in a neighborhood last sold for and when by selecting the properties. A hiker can check the land elevation of the area before setting off on a trip, or a citizen can find details on the aquifer supplying municipal water, all by pointing at a map.
Geographic technologies can combine several variables in a single, custom-made map. For instance, public officials can not only assess the adequacy of public transport to local health facilities by overlaying city bus lines onto...