system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What is a plasma tv and why were they so popular but have now been forgotten?
gpt
Plasma TVs work by using panels made of millions of small gas cells (think mini fluorescent light bulbs).  These panels are relatively difficult to manufacture.

They were very popular because they had superior performance than comparable LCD TVs at the time -- with deeper blacks, more accurate colors, wider viewing angles, and less motion blur.

But over time, LCD TVs became much simpler (thus cheaper) to manufacture than Plasma TVs.  Plasma TVs also required more electricity to run on.  

So Plasma TVs began losing in popularity to the cheaper LCD TVs. 

What finally killed Plasma TVs was the introduction of 4K "Ultra High Definition".   Turns out, making 4K Plasma panels for 50-60" TVs would have been incredibly expensive. 

Because of this high cost, TV manufacturers decided that they would be better off selling 4K LCD TVs instead of Plasma, and invest in newer technologies like OLED.