System integrity is confidence that a device and its software are operating as intended, without unauthorized changes, corruption, or hidden interference. It covers both the hardware state and the software behavior: the boot process, firmware, configuration, sensors, and control logic should all match a trusted baseline.
In cyber security, integrity matters because an attacker does not always need to steal data to cause harm. If they can alter firmware, tamper with configuration, or inject malicious commands, a system may still appear online while behaving incorrectly. Defenders protect integrity with secure boot, code signing, hardware roots of trust, integrity checks, logging, and measured verification after updates or resets. For robots and other exposed devices, integrity is especially important because physical access, noise, or environmental interference can change how the machine acts in the real world.