Monitor Calibration, why is it necessary

The reason is that all monitors display color differently from one another, and almost none of them match the standard viewing conditions for good color. 

Just like anything else, if your display is not up to standards, then the quality won’t be very good, which means your photos won’t look the way they’re supposed to, and neither will your movies and tv shows, games or applications.

ColorMunki smile adjusts your monitor to the right color standards. It does this by measuring a series of colors on your monitor and creating a profile which your computer uses to display color on screen.