Roaming threshold refers to the signal strength at which a client device will switch from one access point (AP) to another in a wireless network. The roaming threshold is usually set in terms of the received signal strength indicator (RSSI). When the signal strength drops below the roaming threshold, the client device will attempt to roam to another AP with a stronger signal. By optimizing the RSSI roaming threshold, the network administrator can ensure that the client device only switches to another AP when necessary, which can help improve network stability and reduce disconnections.