A modern geographical information system will contain both a hardware and a software element. The choice of hardware and software will depend on a number of factors including size of organisation, financial resources as well as the specific requirements for a GIS.

Hardware may consist of a single laptop or multiple workstations linked to a remote server. Peripheral devices such as plotters and scanners may also make up the hardware requirements. The bigger the system the more likely it is able to have the necessary speed to respond to the needs in computing complex queries.

Software may include desktop, mainframe and web based solutions depending on the particular applications involved solving the problems of a specific organisation. These solutions may be running on a variety of operating systems such as windows, unix, linux or mac. The bigger the system the more likely there is for a requirement for a relational database solution such as Oracle, MySQL or PostgreSQL.

Most definitions of a GIS assume that you are talking about computer based systems. However, you need to go back only thirty years before the personal computer to find that GIS meant something completely different.

GIS stands for geographic information system, so by that term we could include any system which uses a geographical element and some associated tabular data. The wikipedia version states that a GIS is a system to capture, store, manipulate, analyse, manage and present all types of spatial and geographical data. This definition doesn't mention anything about computers and so could refer to both manual as well as computerised GIS.