The phrase form–fit–function (FFF) is used in manufacturing to describe the identifying characteristics of a part (a single component that goes into the final build of your product, typically kept on an item master). … In our example, the screw is intended to hold other parts of the product together.

Obsolescence is the state of being which occurs when an object, service, or practice is no longer maintained, required, or degraded even though it may still be in good working order.

The international standard IEC 62402:2019 Obsolescence Management defines obsolescence as the “transition from available to unavailable from the manufacturer in accordance with the original specification”.

Obsolescence frequently occurs because a replacement has become available that has, in sum, more advantages compared to the disadvantages incurred by maintaining or repairing the original.