Preventive maintenance is planned, recurring upkeep — servicing the HVAC, cleaning gutters, testing smoke and carbon-monoxide detectors, checking for leaks — done on a schedule rather than in response to a breakdown. The goal is to extend the life of building systems and catch small problems before they turn into emergency repairs.
Preventive maintenance is usually far cheaper than the reactive alternative: a serviced furnace that lasts years beats an emergency replacement in January, and a caught leak beats water damage. It also supports your habitability duties by keeping essential systems in working order. A good system schedules recurring tasks automatically and stages vetted-vendor routes through the cost cap and acknowledgement rules you set.