Which biometric technology is commonly used for unlocking smartphones?

Facial recognition is commonly used for unlocking smartphones as it utilizes the device's front-facing camera to create a facial map that can be compared to a stored template. This technology allows for quick and convenient access to the phone, enhancing user experience while maintaining a reasonable level of security.

Facial recognition systems analyze various facial features and characteristics, such as the distance between the eyes, the shape of the jawline, and other unique traits, to authenticate the user. The widespread adoption of this technology in smartphones is supported by its ease of use—users simply need to look at their device to unlock it, making it a user-friendly option.

In contrast, while voice recognition is another biometric technology, it is less commonly used for smartphone unlocking due to environmental factors that could interfere with its effectiveness, such as background noise or changes in the user's voice. Retina scans involve capturing the unique patterns in the retinal blood vessels, which is a very secure method but requires specialized hardware not typically found in consumer smartphones. Hand geometry, which measures the shape and size of a person's hand, is more commonly used in controlled access environments rather than on personal devices due to its complexity and the need for specific scanners.