A GIS or Geographical Information Systems captures, stores, analyzes, manages, and presents data that is linked to a location. A GIS is a method by which specialist mapping software  is applied to the areas of remote sensing, land surveying, aerial photography, photogrammetry, and many tools can be used together to make up the specific GIS solution that is needed for a specific project.

A GIS is an information system that integrates, stores, edits, analyzes, shares, and displays geographic information. GIS applications are tools that allow the user to create interactive queries, analyze spatial information, edit data, maps, and present the results of all these operations.

GIS is a powerful tool for collecting and collating datasets enabling consistency and continuity.  GIS is able to process varying types and amounts of data.  It allows the import of various monitoring data sets and statistical analysis of the data.

GIS technology can be used for resource management, asset management, archaeology, environmental impact assessment, urban planning, cartography, criminology, geographic history, marketing, logistics and other purposes. For example, GIS might allow emergency planners to easily calculate emergency response times (i.e. logistics) in the event of a natural disaster, GIS might be used to find wetlands that need protection from pollution, or GIS can be used by a company to site a new business location to take advantage of a previously under-served market.

Spatial data is described in GIS using two main data types. The first is these are Vectors:

In a GIS, geographical features are often expressed as vectors, by considering those features as geometrical shapes. Different geographical features are expressed by different types of geometry:

Points

Zero-dimensional points are used for geographical features that can best be expressed by a single point reference; in other words, simple location. For example, the locations of wells, peak elevations, features of interest or trailheads. Points convey the least amount of information of these file types. Points can also be used to represent areas when displayed at a small scale. For example, cities on a map of the world would be represented by points rather than polygons. No measurements are possible with point features.

Lines or polylines

One-dimensional lines or polylines are used for linear features such as rivers, roads, railroads, trails, and topographic lines. Again, as with point features, linear features displayed at a small scale will be represented as linear features rather than as a polygon. Line features can measure distance.

Polygons

Two-dimensional polygons are used for geographical features that cover a particular area of the earth's surface. Such features may include lakes, park boundaries, buildings, city boundaries, or land uses. Polygons convey the most amount of information of the file types. Polygon features can measure perimeter and area.

Each of these geometries is linked to a row in a database that describes their attributes. For example, a database that describes lakes may contain a lake's depth, water quality, pollution level. This information can be used to make a map to describe a particular attribute of the dataset. For example, lakes could be coloured depending on level of pollution. Different geometries can also be compared. For example, the GIS could be used to identify all wells (point geometry) that are within 1-mile (1.6km) of a lake (polygon geometry) that has a high level of pollution.

The second data type is a Raster:

A raster data type is, in essence, any type of digital image represented in grids. This can be compared a digital photo: a single pixel in a digital photo would be equivalent to a single grid square in a raster. Aerial photographs are one commonly used form of raster data, with only one purpose, to display a detailed image on a map or for the purposes of digitisation (a form of data capture which you would perform in a GIS software). Other raster data sets will contain information regarding elevation, a DEM (Digital Elevation Model), or reflectance of a particular wavelength of light, LAND-SAT (a format of satellite imagery)

For Example: