Most systems are built to be in service over a long period of time. However, planning for productive use over a long period of time is difficult, since the future is fraught with uncertainty due to market, social, economic, political, and technological forces. These forces combine to determine the utility of a system.
Systems may react to these forces by undergoing a stream of changes. Individually, such changes are seemingly innocuous and are made to maintain or increase utility of the system. However, as the changes increase in number, they can become problematic over time. The system may eventually become hard to transform in reaction to forces of change. When changes are too costly or time consuming to make, the system ceases to evolve, does not fulfill its business or mission goals, and falls into obsolescence.