When Apple first introduced the iPhone X, the design was met with its fair share of controversy. Though everyone appreciated the device’s edgeless display, it was hard for many people to wrap their minds around the unseemly notch. Sure, there was no way for Apple to embed the device’s video and Face ID components underneath the display, but many wondered why Apple simply didn’t choose to hide the notch by making the flaps to the left and right of the image sensor black. Instead, Apple all but instructed developers and users to fully embrace the notch.

A week or two after its release, it became overwhelmingly clear that the uproar surrounding the iPhone X notch was overblown. For a vast majority of users, the notch, though perhaps annoying at first, quickly faded into the background and became a non-factor. Before long, we even started seeing a slew of Android handset manufacturers start to copy the iPhone X design, right down to the notch itself. To this point, just a few weeks ago a photo featuring 20 Android handsets with iPhone X-style notch designs began making the rounds.

Interestingly, not all notch designs are created equal and some of the Android copycats we’ve seen thus far have sported horrible looking implementations. As it turns out, there’s more to the iPhone X notch design than meets the eye. Touching on this very point, I recently stumbled across an old Medium article from Brad Ellis who explains why the notch on the iPhone X looks a lot more aesthetically pleasing than many competing designs.

As Ellis remarks, there are a myriad of ways to implement a notch design, some markedly better than others. In turn, the direction Apple chose with the iPhone X just seems to work for reasons Ellis explains in detail.

Here’s where the nerd part comes in, iPhone X rounded screen corners don’t use the classic rounding method where you move in a straight line and then arc using a single quadrant of a circle. Instead, the math is a bit more complicated. Commonly called a squircle, the slope starts sooner, but is more gentle.

Now let’s talk about the notch itself. The left and right sides have two rounded corners. Because of the curve falloff, one curve doesn’t complete before the next one starts — they blend seamlessly into each other. As a result, no tangent line on this edge actually hits a perfect vertical.

If you’ve been curious as to why the iPhone X just seems to look smoother than a slew of Android copycats, you’ll definitely want to check out Ellis’ entire piece — which includes a number of illustrative examples — over here.