Native resolution

Native resolution is the Maximum and the best resolution supported by the entire-display
And Native resolution is only used in LCD displays and OLED and even All Flat-panel displays
Since the CRTs doesn't have any native resolution , So ,There are many people uses the CRTs because they supports a lot of resolutions.
Why CRTs doesn't have Native resolution?
The CRT (Short for Cathode-ray tube) is a Vacuum tube which contains one or more electron guns , Which lights the phosphor , When it's struck by electrons.
Most and modern color CRTs Uses 3-Electron guns to create all the colors you see on your screen
Anyway,The 3-electron guns uses the Magnets to beam the electrons , so they can sweep faster across the shadow mask and the phosphors and create the pictures you see on a CRT monitor.
That actually happens so quickly , depending on higher-refresh rates (60Hz or more)
How many times they scan the entire screen,are described by the Hertz of the refresh-rate.Keep in your mind , That 60Hz means "The electron guns , Sweep across the entire screen seixty(60) times per second
and the white color is created by "Three primary colors" and they are "Red and green and blue"
While all Mono-chrome CRT's doesn't have Maximum resolution , but All color-CRT's have Maximum resolution supported by the shadow-mask , Less Pixel pitch , means more Maximum supported resolutions by the CRT
-Insert PlayZ.
This one is from Wikipedia , Not from me ,So I hopefully that it helps you.