The refresh rate is basically how many times a second the TV redraws the picture on the screen. A 60 Hz set redraws the picture 60 times a second. A 120 Hz refresh rate redraws the picture 120 times a second. The issue is that most of the material you're watching doesn't match the refresh rate. The material focuses more on frames per second.
A 60 Hz TV would get 60 frames per second fed into it in a perfect world. Every time it draws the picture, the picture would be slightly different. Broadcast television broadcasts at 29.97 frames per second. So, your 60 Hz set draws the same picture twice for every frame. A 120 Hz set would draw the same picture four times in a row without digital help. Movies are typically shot at 24 frames per second, so the TV draws the same image five times per original frame.
If you're watching sports on a broadcast network using a good over-the-air antenna, you're probably getting 29.97 frames per second. If you're watching cable or satellite, you're probably getting less as they compress their signals in various ways. So, why does a 120 Hz TV appear to be smoother and have less blur? The TVs cheat.
A 120 Hz HDTV will grab a few images as they come in and hold them and compare them one to the next. For the sake of argument let's label one second of images 1-30 (thirty frames per second.) The HDTV will be drawing pictures 1-120 in a second from those thirty frames. So, from the data from images one and two they have to create four pictures. The TV gets image one and holds it. It then gets image two and compares it to image one. It's looking for differences between the two. When it goes to draw image one, it will show that image as it came in. Then it knows what image two will look like so it creates images for pictures, 2, 3, and 4, that will lead into image 2. The TVs pretty much fill in the blanks using their best guess as to what happened where they don't have data. It usually works pretty well.
As a viewer, it may make the picture look smoother and less blurry. In reality, you're seeing the same real images as everyone else. Your TV is just filling in the blanks with its best guesses. Your TV is just getting 29.97 frames per second. (At best. Once again, cable and satellite providers tend to compress images.)
The only pure 120 Hz images that I'm aware of are on the newest gaming consoles and even those require the software creator to produce 120 Hz software for the consoles. Many don't. Anything else is likely at 29.97 frames per second or slower so the higher Hz rate is less apparent.
So, should you buy a 120 Hz set? Maybe. If you notice blurring and smearing now on your 60 Hz set, then yes. If you think your 60 HZ set looks fine, then don't spend the extra. And it's not that much extra these days. You can get a 50" 120 Hz TCL set for $450 these days. Sony has a 43" HDTV with pretty much everything for $598. Give it a year or two and every HDTV will be 120 Hz. Electronics prices and features get cheaper each and every year. What was state-of-the-art and very expensive ten years ago can be hard for a tenth of the cost now.
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