I remember my early Windows and Palm OS portable devices. These came with a stylus because the screen worked on contact; my favorite stylus was easily the expandable one on my Palm Tungsten T (and the T2, oh and the T3 as well). Then, Apple started using capacitive screens and the stylus largely went away until Samsung reinvented the technology for the late 2011 Galaxy Note phablet. However, Samsung didn't just use any old stylus; instead their product is called the S Pen. Like the original Galaxy Note has evolved to become the Galaxy Note 4, so too has the S Pen evolved. This post is more about the hardware technology that goes behind the S Pen software built into the Note series of devices.
In the latest iteration, Samsung are making much of the sensitivity of the fourth generation S Pen being double what it was before. You see, the S Pen doesn't work through contact but instead through the screen understanding where the object is. The S Pen can be floating above the screen, which is how Air View works. It's an electromagnetic induction system located behind the Note's screen. This system consists of tiny coils and a circuit board that responds; in some limited respects, the technology is similar to that of Qi wireless charging or NFC as it uses a very short range passive / active signal.
The technology benefits from Samsung's investment into Wacom, where they bought 5% of the company last year. It is sensitive enough to understand the location, angle and pressure being applied from the S Pen to the screen. This is why we can apply any screen protector we wish to the Note's display. And it's this sensitivity to pressure where Samsung have doubled things as it can now determine the level in 2,048 stages, up from 1,024 in the previous generation Note 3. It's unlikely that the human hand can graduate a pressure across a thousand steps let alone two thousand, however it should make for a smoother user interface when using the S Pen.
Of course, the clever S Pen technology is nothing without Samsung's clever software that's designed to make the Note series of devices productive, from Air View, Air Command and Pen Window. The S Pen can now act as a mouse when it comes to selecting text and objects.