Bluetooth is an open standard for short-range radio frequency communication. If your mobile device has Bluetooth capability, turn off or set the Bluetooth connection capabilities to “nondiscoverable.” When in discoverable mode, Bluetooth-enabled mobile devices are “visible” to other nearby devices, which may alert a hacker to target them. When Bluetooth is turned off or in nondiscoverable mode, the Bluetooth-enabled mobile devices are invisible to other devices not authorized to access or monitor the data in your device. NIST has issued a Guide to Bluetooth Security, SP 800-121 Rev 1.