Low-voltage DC, or direct current at relatively low voltages, is the power format used by many small electronics: USB devices, sensors, embedded boards, routers, and other lab gear. In practice, it usually comes from adapters, batteries, or negotiated power systems such as USB-C PD. Because these devices are often sensitive to voltage drop, ripple, and polarity, the quality of the power supply matters as much as the nominal voltage.
In cyber security, low-voltage DC matters because many targets and tools depend on it: IoT hardware, access-control devices, and forensic or test equipment. Attackers may abuse weak or unstable power to trigger resets, create unpredictable behavior, or hide malicious activity behind a device fault. Defenders check low-voltage DC with meters and analyzers to confirm the right voltage, current, and cable negotiation, and to spot anomalies before they become reliability or safety problems.