Wear is the gradual loss of performance or integrity caused by repeated use, tension, heat, or friction. In cybersecurity, the term matters because many systems depend on physical parts that age: hard drives, flash cells, batteries, fans, cables, sensors, and even smart-card contacts. As wear increases, failures become more likely, logs may be lost, authentication devices may misread, and critical controls can drift out of spec.
Attackers can sometimes exploit wear indirectly by stressing equipment with repeated operations, while defenders plan for it by tracking device age, replacing consumables, and designing redundancy. Good security practice assumes that worn hardware is less reliable and may produce outages that look like incidents. Lifecycle management, health monitoring, and timely replacement help keep degraded parts from becoming a weak point in availability or trust.