An always-on device is hardware that remains powered and network-connected for long periods, often with little user attention. Examples include TV boxes, routers, cameras, smart speakers, and other home or office appliances that are expected to run continuously.
This matters in cyber security because a device that is always online is a stable target for abuse. If attackers install hidden software, they can quietly use it for proxy traffic, ad fraud, scanning, or command-and-control without needing to re-compromise it each time. In real attacks, these devices are attractive because they blend into normal household or business traffic and can be repurposed as low-cost infrastructure. Defenders watch for unusual outbound connections, unexplained bandwidth use, and background services that persist across reboots. Strong firmware control, network monitoring, and removing unnecessary internet exposure help reduce the risk.