A geographic information system (GIS) refers to any system that records and analyzes information linked to a geographic location. A GIS then presents this data in a visual format. GIS mapping stores, integrates, and displays geographic information, and allows users to search for specific queries and draw conclusions from the analysis of the spatial information and data presented by the map.

The use of GIS mapping technology can be seen today in GPS devices and online mapping applications like Google Earth. The study of geographic concepts and mapping systems is called geographic information science, in which universities around the world offer degrees.

Displaying visual data on a map according to the information’s geographical location, and then analyzing and drawing conclusions about that information is a well-established idea: visual icons on maps have represented real-life features of a region since ancient times.

In the late 1990s, GIS data was generated by large computers and used for maintenance of internal records. GIS software came as a stand-alone product that required its own piece of hardware to operate. GIS data couldn’t be delivered over a network, but had to be accessed through a specific device. However, as Internet technology became increasingly popular and demand for easier access to geographical data swelled, the GIS software industry changed its format so that data could be delivered across a network. Today, GIS software is not a stand-alone feature, but rather is integrated into a combination of other applications.

Digitization
Heads-up digitization is the most common method of GIS data creation. This is a method in which a hard copy of a map or a schematics plan of a certain geographical region is transferred into digital form through a computer-aided design program and the use of geo-referencing capabilities. The use of orthorectified satellite and aerial imagery is one of the most widely used forms of heads-up digitizing. Using orthorectified images from satellite and aerial shots, GIS programs can place data about a certain geographical location or region directly on top of the aerial image. Today, heads-up digitization technology is capable of adjusting lens focus and angle so that the photograph taken by a satellite or a plane will actually match the surface distances and features of a region.

GIS technology is being implemented in many different disciplines. The active market for map-based applications has led to cheaper GISs as well as the rapid, continual improvement of GIS hardware and software. These improvements, in turn, make it possible for the market for GIS technology to increase even more.

With GPS capabilities becoming increasingly common in cell phones, computers, and vehicles, the demand for location-based services has risen as well. Many consumers today are accustomed to finding directions to a restaurant, theater, or other point of interest online. But they can also search for a specific location even when they are away from the house. Information is displayed on a screen along with the user’s current location.

GIS mapping technology is also helping governments and social groups identify social, economic, and political trends by studying how those factors relate to a particular region’s geographical information.

GIS data displays use symbols to represent real-life objects or geographical features. There are two basic categories into which all real-life objects represented on a map fall: discrete objects, such as a building or river, and continuous fields, which are features that are neither static nor locked to a specific place. Rainfall, elevation, and weather are good examples of features that fall under the category of continuous fields. GISs store data and layer it atop digital geographical visual displays via two methods: raster and vector.

Raster
Raster data is any kind of digital image displayed in grids. Raster data is not concerned with producing an exact representation of reality, but instead reflects an abstraction of reality. Aerial photos are an example of a commonly employed form of raster data. The purpose of an aerial photo in geographic information systems is to display a detailed map or to provide an image to be digitized. Raster datasets contain elevation information, or a digital elevation model (DEM) as well as discrete values and continuous values information.

Raster data can be stored in several formats, including standard file-based forms like TIFF or JPEG, and also as binary large object (or BLOB) data that’s kept in a relational database management system. When properly organized and categorized, raster data can be searchable and easy to find.

Vector Mapping
Vector mapping is a fairly straightforward method of displaying data on a map. It uses points for small discrete values, lines for rivers and other tangible but large discrete values, and polygonal shapes to represent aspects of a terrain that occupy a whole area. Features like lakes and certain aspects of the weather are given polygonal representations on vector maps. In essence, vector mapping divides the types of places in a map and codes them using geometric shapes.

• Points – Points are zero-dimensional. They are used to show geographical data best expressed as a static location, which could serve as a point of reference for those looking to orient themselves. Houses, wells, and places of interest on a map are usually represented by points. Other than its location, you cannot measure any other feature of the object using a point as its visual representation.
• Lines – Lines are one-dimensional and they can be used to represent roads or moving bodies of water in mapping. Railroads, trains, and anything having to do with a system of land transportation will be represented by vector lines. Lines measure an object’s distance or length.
• Polygons – Polygons are two-dimensional graphics used to represent area. A large lake, a state boundary, or the region affected by a flu epidemic, for example, can be represented, and its area and perimeter measured, by polygons.

These geometries work in conjunction with other datasets that describe more detailed features of the objects being displayed. For example, polygon areas on a map that represent lakes could be color coded, with each color assigned to a different level of depth, pollution, salinity, or any other piece of information to be conveyed on a GIS display.

GISs can take all of this information and categorize it in different ways to help people find information. For example, a GIS can help a user find the location of a point of interest, such as a restaurant, in relation to another point of interest, such as the user’s house.