Geographic information systems
A geographic information system or (GIS) is a system designed to capture, store, manipulate, analyze, manage, and present spatial or geographical data. The acronym GIS is sometimes used for geographic information science (GIScience) to refer to the academic discipline that studies geographic information systems and is a large domain within the broader academic discipline of geoinformatics. What goes beyond a GIS is a spatial data infrastructure, a concept that has no such restrictive boundaries.
In general, the term describes any information system that integrates, stores, edits, analyzes, shares, and displays geographic information. GIS applications are tools that allow users to create interactive queries (user-created searches), analyze spatial information, edit data in maps, and present the results of all these operations. Geographic information science is the science underlying geographic concepts, applications, and systems.
Geographic data can be stored in a vector graphics or a raster graphics format. Using a vector format, two-dimensional data is stored in terms of x and y coordinates. A road or a river can be described as a series of x,y coordinate points. Nonlinear features such as town boundaries can be stored as a closed loop of coordinates. The vector model is good for describing well-delineated features. A raster data format expresses data as a continuously-changing set of grid cells. The raster model is better for portraying subtle changes such as soil type patterns over an area. Most geographic information systems make use of both kinds of data.
GIS is a broad term that can refer to a number of different technologies, processes, and methods. It is attached to many operations and has many applications related to engineering, planning, management, transport/logistics, insurance, telecommunications, and business.  For that reason, GIS and location intelligence applications can be the foundation for many location-enabled services that rely on analysis and visualization.
GIS can relate unrelated information by using location as the key index variable. Locations or extents in the Earth space–time may be recorded as dates/times of occurrence, and x, y, and z coordinates representing, longitude, latitude, and elevation, respectively. All Earth-based spatial–temporal location and extent references should, ideally, be relatable to one another and ultimately to a "real" physical location or extent. This key characteristic of GIS has begun to open new avenues of scientific inquiry.
GISs do these kinds of things:
- They accept geographic input in the form of scanned-in and digitized map images. Often this data is supplied by a source that may own maps and has already digitized them.
- They rescale or otherwise manipulate geographic data for different purposes.
- They include a database manager, usually a relational database management system (RDBMS).
- They include query and analysis programs so that you can retrieve answers to simple questions such as the distance between two points on a map or more complicated questions that require analysis, such as determining the traffic pattern at a given intersection.
- They provide answers visually, usually as maps or graphs. = Spatial data =
Spatial data, also known as geospatial data, is information about a physical object that can be represented by numerical values in a geographic coordinate system.
- "Geographic Information Systems as an Integrating Technology: Context, Concepts, and Definitions". Kenneth E. Foote and Margaret Lynch, The Geographer's Craft Project, Department of Geography, The University of Colorado at Boulder. http://www.colorado.edu/geography/gcraft/notes/intro/intro.html. Retrieved 21 Apr 2015.
- Clarke, K. C., 1986. Advances in geographic information systems, computers, environment and urban systems, Vol. 10, pp. 175–184.
- "Geographic information system: Old principles with new capabilities". 2011. pp. 1–6. doi:10.1057/udi.2010.25. http://www.palgrave-journals.com/udi/journal/v16/n1/abs/udi201025a.html.
- Goodchild, Michael F (2010). "Twenty years of progress: GIScience in 2010". Journal of Spatial Information Science. doi:10.5311/JOSIS.2010.1.2.
- Rouse and Fontechhio.,(Accessed October 19 2016)."What is spatial data?".http://searchsqlserver.techtarget.com/definition/spatial-data