A guest network is a separate Wi-Fi segment on a home or small-office router for visitors, smart devices, or other less-trusted equipment. It usually has its own SSID and, when configured correctly, cannot directly reach the main LAN, shared files, printers, or router management page.
This matters because one compromised device should not expose everything else on the network. Attackers often look for flat networks where a vulnerable phone, camera, or laptop can be used to probe internal systems. A guest network reduces that risk by creating a simple trust boundary. Defenders use it to isolate guests, IoT devices, and temporary connections, often combined with client isolation, strong Wi-Fi passwords, and restricted access to local resources. It is useful only if the router settings actually block internal access.