For the most recent iMacs, Apple developed a new keyboard, with a fingerprint scanner at the top right. This so-called Magic Keyboard with Touch ID is now also for sale separately.
Log into your Mac without remembering your password or use it to identify Apple Pay, for example.
The Touch ID functionality only works on Macs with an Apple processor, so not on models that still have an Intel CPU under the hood. A list of supported computers find you here under the Compatibility heading.
Price
The version without numpad costs 159 euros and the variant with numerical part costs about three tens more.