A pre-shared key (PSK) is a secret configured on a Wi-Fi access point and shared with users or devices that need to join the protected network. In common home and small-office Wi-Fi, it is the network password used during connection and helps authenticate devices and protect wireless traffic.
A strong, unique PSK helps prevent unauthorized access, but it is not a fix for vulnerabilities in router setup services that can be reached before normal authentication. Attackers may target such services without knowing the Wi-Fi password, so defenders should also install vendor or ISP firmware updates, disable unnecessary setup features, and use a long, hard-to-guess PSK.