Both Bluetooth and Wi-Fi radios operate in the 2.4-GHz frequency range, so they could momentarily try to use the same frequency. The frequency hopping technique that Bluetooth wireless technology uses prevents such a conflict from causing a complete connectivity loss, but it could reduce the transfer rates for both radios.
Version 2.0 of the Bluetooth specification supports AFH. With AFH, a Bluetooth radio senses traffic from other types of radios, marks the busy channels as ”noisy,” and avoids those channels as it hops frequencies. Windows Vista and later improves AFH even further by treating the ”air” as a shareable spectrum. This feature lets wireless technologies such as Wi-Fi adapters report which channels they intend to use. When the Bluetooth stack becomes active, it is notified of the reported in use channels and marks them as noisy.