In Short

Touch ID is Apple's biometric fingerprint authentication technology. With it, the Home button can now unlock your iPhone 5s and authorize your purchases on the iTunes Store. A capacitive ring activates the scanner on contact which then takes a high-resolution picture of your fingerprint. That fingerprint is then converted into a mathematical formula, encrypted, and carried over a hardware channel to a secure enclave on the Apple A7 chipset. If the fingerprint is recognized, a "yes" token is released. If it's not, a "no" token is released.

Touch ID is Apple's biometric fingerprint authentication technology. With it, the Home button can now unlock your iPhone 5s and authorize your purchases on the iTunes Store. A capacitive ring activates the scanner on contact which then takes a high-resolution picture of your fingerprint. That fingerprint is then converted into a mathematical formula, encrypted, and carried over a hardware channel to a secure enclave on the Apple A7 chipset. If the fingerprint is recognized, a "yes" token is released. If it's not, a "no" token is released.

Neither the 2013 iPad Air nor Retina iPad mini shipped with Touch ID, possibly because Apple couldn't yet produce them in sufficient quantities. Perhaps the 2014 versions will rectify that...?

In the perpetual battle between security and convenience, where many people would rather go without a passcode or strong password than fuss with anything complicated on mobile, Apple's Touch ID fingerprint identity sensor aims to do for authentication what iCloud did for backup and restore - make it easy enough that people will actually use it.