Samsung's new Galaxy Note 7 comes with all of the features that the Note smartphone line is known for. It has a large display, works with the S Pen stylus, and is water resistant. But it also has another, long-rumored feature that is slowly finding its way into more consumer electronics: an iris scanner.

The Galaxy Note 7 uses both an IR camera module and a proximity sensor to recognize when its owner is holding the phone up to his or her face (from 25 to 35 centimeters, or about a foot away). The camera can quickly scan the owner's iris and, based on biometric data stored locally on the phone, will unlock the device. Note 7 owners can also store personal documents, like contracts or a copy of a passport, in a secure folder on the phone that can only be unlocked with an iris scan.

It's not the Note 7's primary security feature, but Samsung is calling it an extra layer of protection

The iris scanner isn't the smartphone's primary security feature, Samsung says; it's an extra layer of security alongside the now widely adopted fingerprint sensor, and it's completely optional. But the inclusion of the iris scanner comes at a time when the security of a smartphone's fingerprint sensor is being tested. Authorities, researchers, and hackers have all demonstrated ways in which 3D-printed molds, made from images of a person's unique fingerprint, can be used to unlock fingerprint-protected smartphones.

Iris scans aren't completely fool-proof — and even Samsung won't say outright that they're more secure than fingerprint scanning — but some researches have pointed out that the randomness in irises make them more difficult to forge. (They're also a controversial topic, with government agencies launching pilot programs around iris scanning without fully assessing the potential impact on privacy.)

Iris scanning makes it way into the mainstream

And iris scanning is making its way into more consumer electronics. Microsoft's Windows-based Lumia 950 and 950XL smartphones, and select Windows 10 laptops that support Windows Hello, now have iris scanning features, and some reports suggest that iris scanning could come to future iPhones.

In the near term, though, Samsung may just be the manufacturer that brings iris scanning to the mainstream. The company's Galaxy S7 flagship phone reportedly outsold Apple's iPhone in the US last quarter, and Samsung has said that its "phablet" category is its fastest-growing subset of mobile phones. It's an ancillary feature on the Note 7, for sure, but it's one that users may grow accustomed to pretty quickly.