How are personal mobile electronic devices commonly used as access cards?

Personal mobile electronic devices commonly serve as access cards primarily through the technology of Near Field Communication (NFC) and Bluetooth. When a mobile device uses NFC, it can communicate wirelessly with a compatible access control reader when they are in close proximity. This interaction typically involves a secure handshake between the device and the reader, allowing for seamless authentication and entry.

Bluetooth technology enhances this capability further by enabling longer-range communication, allowing users to unlock doors or gain access without needing to physically tap their devices against a reader. The integration of these technologies into mobile devices has made access control more convenient and secure, as users can simply use their smartphones or smartwatches to gain access, rather than carrying separate physical access cards.

Other methods like QR codes, tethered devices, and USB connectivity do not offer the same level of convenience and efficiency. QR codes often require scanning and do not support real-time encrypted communication, tethered devices typically involve physical connections limiting mobility, and USB connectivity is less common for mobile access due to compatibility issues and the need for physical interaction.