Passcodes restrict unauthorized access to the device. Once a passcode is set, each time you turn on or wake up the device, it will ask for the passcode to access the device. iOS devices support simple as well as complex passcodes. iOS 9 released the option to use a six-digit simple passcode instead of the legacy four-digit option. The iPhone 5S and later also supports Touch ID fingerprints as a passcode, which are backed up with a simple or complex passcode. The iPhone X and later support a new biometric way of locking the device—Face ID—so that users can use their faces as the passcodes. And it's even more secure, as the chance that a stranger will unlock your iPhone with Touch ID is 1 in 50,000, but with Face ID it is 1 in 1,000,000.