At the beginning of the 21st Century, it is reasonable to assume that most organisations of any size will employ information technology to a greater or lesser degree. This implies that they have made a considerable investment both in developing the information system itself, and in training their employees to operate and maintain the system. The users are familiar with its operation, the IT staff are familiar with the technology, and management have a good grasp of the capabilities of the system.

The implementation of a new system, or even a major upgrade to an existing system, is likely to be expensive and fraught with risk. Hardware and software may need to be replaced or upgraded, staff may need to be re-trained, and the network cabling may have to be ripped out and replaced. There are, of course, a number of reasons why organisations are prepared to undertake the expense and face the risks of introducing a new system.

The system may no longer be fit for its intended purpose. This may occur for a number of reasons. The work of the organisation may have changed or evolved over a period of time to such an extent that the existing system is no longer ideally suited to current work practices. Growth, too, is an inevitable and desirable aspect of any successful enterprise, and invariably involves an increased number of staff, a higher volume of working data, and a greater number of business transactions in a given period of time.

The organisation's business may have grown to such an extent that the system can no longer cope with the workload. External factors can also put additional pressure on the system. New government legislation, for example, may require that more stringent security measures are implemented for certain types of data, or require changes to the type of information that is held on the system, or increase the period for which certain types of financial information must be held.

Information technology is probably one of the fastest changing fields of human endeavour. Computer hardware and software, network technology, and global communications systems are constantly evolving in terms of both the speed at which they operate and the functionality offered. If a competitor is using a more advanced system that provides greater efficiency, reduced cost, and enhanced capabilities, they are clearly at an advantage.

Customers, too, often provide the impetus for change by demanding that the systems used by their suppliers are upgraded to facilitate a timely and efficient exchange of data. Many software vendors will only support a particular version of a software package for a limited period of time. This, together with the fact that older software packages are often unable to take full advantage of advances in hardware, means that the system software must at some point be updated.