Smartphone makers love pushing limits, and over the years we've seen them fight to one-up each other by delivering the biggest and highest-resolution screens, or cameras with the most megapixels. Over the course of the past year or so the latest incarnation of this trend has emerged, with manufacturers launching phones featuring some of the smoothest, highest-frame-rate displays ever. Now Samsung finds itself at the front of this effort, as it launches the Galaxy S20 series with 120Hz displays. What's so great about this tech and why should you care? Let's take a look.

All video screens work by displaying a series of still images in quick succession — show enough of those, fast enough, and you get the appearance of motion, like thumbing through a flipbook. Traditionally on a smartphone, that happens 60 times a second — or at 60Hz. While hertz (Hz) can measure any repeating action, for our purposes here it's more or less synonymous with “frames per second.”

When you're interacting with your smartphone's screen operating at 60Hz, the picture looks pretty good. Depending on how powerful your phone is and what you're up to you may occasionally see some stuttering performance, but by and large the illusion of motion is successful — you swipe between apps, drag down notifications, and all these UI elements appear to move around in response to your control.

But just because something looks good doesn't mean it can't look better. Think about the evolution we saw as high-res screens became available: Text on a phone with a 720p display may be perfectly readable, but as you move up to 1080p and even 1440p, curves become more rounded and less blocky, subtle serif details emerge, and you end up with something that's just more refined — more natural-looking — than you'd get out of a system with a lower resolution.

We can draw a direct comparison between that and the impact of high-refresh-rate (aka>60Hz) screens, swapping the increase in spatial resolution for increased temporal resolution — that is, displaying frames faster.

Smartphones with 90Hz screens were landing back in 2018, like the initial ROG Phone. Compared to a 60Hz display, any motion you see on a 90Hz panel is created with 50% more frames. And because those frames are all displayed in the same amount of time, our eyes don't have to “fill in the gaps” as much, and the end effect is that the animation appears smoother.

That improvement is only more pronounced when we step up to 120Hz screens, as we find on Samsung's Galaxy S20 family. Operating twice as fast as a 60Hz display, the illusion of motion is achieved with even finer precision.

To be fair, there is a trade-off to be had here, and while the 120Hz screen on the S20 may look great, it takes a lot of energy and processing power to move all those pixels. As a result, users are asked to make a choice: either enjoy the full-res 1440p panel at the standard 60Hz, or take a slight resolution hit down to 1080p and operate the screen at full 120Hz speed.

Of course, the most buttery smooth refresh rate in the world isn't going to matter much if the phone's not very responsive and just can't keep up with you. Limiting resolution to 1080p helps a bit there, but Samsung also helps the S20 out by giving the phone an extra-high-refresh-rate touchscreen sensor, operating at 240Hz. That lets the handset monitor your finger position even faster than it can update its 120Hz screen, making sure that you're always in control of the action.

Between the two of these systems, the S20 looks like one of the best-equipped phones on the market to deliver an exceptionally sleek, responsive user experience.