A color matching system used by the printing industry to print spot colors.
Most applications that support color printing allow you to specify colors by indicating the Pantone name or number. This assures that you get the right color when the file is printed, even though the color may not look right when displayed on your monitor. PMS is color-accurate because the specified color is NOT made up of other colors, as in the four-color process method, where cyan, magenta, yellow and black are used to build other colors.
use it in real life: Lets say you have a specific color you want for your logo and you want your logo printed on a brochure. To be sure the color is accurately reproduced whenever or wherever it is printed, you would choose a PMS color. Its like you have a big bucket of just that color and they pour that bucket into the printing press. No other colors combine with it, so its always pure and always the same.