3.2. Common GIS data types

The geometric aspect associated with GIS data is what separates geographic databases from other databases (Burrough and McDonnell, 1998). Geographic databases are sometimes referred to as geodatabases, which refer to databases specific to geographic data. Until recently, most GIS data were generated and distributed by government or private industries and had to be purchased. Now, there are many sources for downloading free data (Table 2). The amount of available data largely depends on the area of interest, as urban areas tend to have more data available than rural or remote areas. Another important aspect of geographic data is the metadata. Metadata are the information provided about the data, thus, data about data (Burrough and McDonnell, 1998). When downloading data online or receiving data from an outside source, metadata are important for obtaining knowledge about when the data were created, for what purpose, by whom, and using which coordinate system, among other things. Without this information, data would be of limited use only. In the following section we will introduce some of the common file formats and extensions, as well as some geographic data examples. The possibilities of types of data in GIS are becoming broader as the technology develops. The following is a non-exhaustive list that shows some of the data types you may encounter when using GIS.

Table 2. Names, websites, and types of data available from various free data sources.



Types of data

Aster GDEM


30 m DEM of the world



Layers created from Open Street Maps for various places in the world

Corine Land Cover 2006 (European Environment Agency (EEA))


Land cover raster data for Europe 100 m and 250 m resolutions

European Environment Agency (EEA)


Land use, economics, natural resources, water, etc.

FOSSGIS (Free and Open Source Software for GIS)


Many from multiple sources

Global Land Cover Facility (GLCF)


Satellite imagery, products derived from satellite imagery, vector products

Open Street Map



Global or individual country or state map data

Swisstopo Landsat Image




Digital satellite mosaic

United Nations Geographic Information Working Group (UNGIWG) Second Administrative Level Boundaries (SALB)


International borders

United States Geological Survey (USGS) Earth Resources Observation and Science (EROS) Center


Aerial Photography

Satellite Imagery


Land Cover

Digitized Maps

Image Gallery Collections


3.2.5. Thematic vector data