Keeping something in a state of usefulness or readiness is known as?

The term that best describes keeping something in a state of usefulness or readiness is maintenance. Maintenance involves actions taken to preserve or restore the functionality of equipment, ensuring that it operates effectively and safely throughout its intended lifespan. This can include regular inspections, repairs, and necessary adjustments that prevent deterioration and extend usability.

Preparation, while related, focuses more on the steps taken ahead of time to get ready for a specific task or event, rather than the ongoing process of keeping something in good working order. Functionality refers to the ability of something to perform its intended function rather than the efforts made to maintain that capability. Recovery typically signifies the process of returning something to a normal state after it has been impaired or damaged, which again is not aligned with the continuous upkeep implied by maintenance.