TV Refresh Rates Explained: 60Hz, 120Hz, and Beyond

pcmag.com:

If you're in the market for a TV, you've probably heard a lot about "speed." When ads and reviews talk about how fast a TV is, they're referring to the panel's refresh rate, or how often it changes the picture. Television and movies don't show actual motion so much as they do dozens or hundreds of distinct images per second like a huge flipbook (or, well, a reel of film). The more images—or frames—a TV displays per second, the faster it is.

Faster refresh rates should result in smoother, better TV, right? Logic and marketing agree on this correlation, but the reality is more complicated.

Before we can clear up the confusion, we must establish two important things about video. First, you can't add detail beyond what is already in the source footage (you can synthesize information with image processing, but it doesn't actually add detail that isn't there; it only polishes it a bit). Second, the vast majority of video source footage doesn't exceed 60Hz. When you stream a movie online or watch a Blu-ray disc, you see a 1080p or 4K picture at up to 60 frames per second (fps), though it is more likely either 24 or 30fps.

For movies specifically, especially ones that were recorded on film, the original footage is captured at 24 frames per second and then upscaled to 30fps through a process known as 3:2 pulldown, which distributes the source images so they can be spread across 30 frames every second instead of 24. Those frames are then interlaced (combined and shuffled) to 60 frames per second to match the 60Hz refresh rate of most TVs. Of course, any content that was originally recorded at 60 frames per second can match a 60Hz TV's refresh rate without any pulldown or interlacing.

Once a TV's refresh rate rises above the rate