Displays aren't static. Content and motion appear smooth on your phone’s screen because every pixel constantly updates to display the latest content from your handsets processor. But this doesn't happen randomly. Panels update their content at regular intervals, known as the refresh rate.

The refresh rate measures the period of time between a phone’s display updates. In other words, how often and quickly the content on the screen refreshes. Measured in Hertz (Hz), the refresh rate counts the number of times the display fully refreshes every second. A 60Hz display refreshes 60 times per second, 90Hz is 90 times per second, 120Hz is 120 times per second, and so on. So a 120Hz display refreshes twice as fast as a 60Hz panel and 4x faster than 30Hz.

What 60Hz, 90Hz, and 120Hz?

The difference is basically the way in which these panels refresh content being played on them. For instance, the 60Hz refresh rate display got its name on its working mechanism. A 60Hz display refreshes its content 60 times per second or 60 frames per second. We can't see the frames changing because we can only see 5 frames per second changing.That was smooth, but wait until you hear that a 90Hz panel refreshes the content at 90 frames per second. A 120Hz panel, on the other hand, refreshes its content 120 times per second, making it look much smoother.

Drawback of High Refresh rate:

Higher frame rate gaming requires a beefy, energy-hungry processor too. This ensures that the graphics frame rate keeps up with the high display refresh rate. The game you’re playing also needs to support high refresh rates too. A 120Hz display won’t benefit from a game capped at 30 frames per second.

High refresh rates reduce battery life and effect the phone processor too and 

However, newer handsets with more efficient displays provide decent battery life, thanks to adaptive 90Hz and 120Hz refresh rates. This is helping to lessen the trade-offs associated with early high refresh rate panels

NOTE:

Pictures are from internet source i.e: GOOGLE

That's All for the day regarding Refresh Rate and types of Refresh rates any doubts regarding let me know in comment section

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