There are various technologies for data input and output but this section concentrates on software applications to handle spatial data and desktop GIS in particular.

According to the 1987 Chorley Report the software comprising GIS has functions to:

    • capture,
    • store,
    • check,
    • integrate,
    • manipulate,
    • analyse and
    • display spatially referenced data.

Or rather, this is how the GIS developer looks at the situation. The real purpose of GIS, like that of all information systems, is to improve the user's ability to make decisions. Let us consider the role of GIS for a user in his/her organisation. Some might see it a single universal tool - a one-stop shop for handling geospatial data. Many more might use GIS for part of their job and select some tools as appropriate. This suggest a view of GIS as 'a chain of operations from planning the observation and collection of data, to storage and analysis of the data, to the use of derived information in some decision-making process' (Star and Estes, 1990). Using this definition it is possible to group operations into (at least) three tasks:

geodata acquisition & management,
geocomputational analysis,
geoinformation visualisation & communication

In this sense, within a typical organisation GIS software tools are used to... manage spatial data as part of the assets of the organisation or... process data to generate new information or... communicate ideas and findings to others within or outside the organisation. It follows that you will need to understand which functions are used in each of these tasks.

Department of the Environment, 1987. Handling Geographic Information: Report to the Secretary of State for the Environment of the Committee of Enquiry into the Handling of Geographic Information, Chairman: Lord Chorley, p. 7.
Star J and Estes J, 1990. Geographic Information Systems: An Introduction. Englewood Cliffs, New Jersey: Prentice Hall.