Creep

Feature creep is the proliferation of features in a product such as computer software. Extra features go beyond the basic function of the product and so can result in baroque over-complication rather than simple, elegant design.

The most common cause of feature creep is the desire to provide the consumer with a more useful or desirable product, in order to increase sales. However, once the point at which a product does everything that it is expected to do is reached, the manufacturer is left with the choice of adding unneeded functions or sticking with the old product.

Mission creep is the expansion of a project or mission beyond its original goals, often after initial successes. The term often implies a certain disapproval of newly adopted goals by the user of the term. Mission creep is usually considered undesirable due to the dangerous path of each success breeding more ambitious attempts, only stopping when a final, often catastrophic, failure occurs. The term was originally applied exclusively to military operations, but has recently been applied to many different fields, mainly the growth of bureaucracies.