Spot color is a solid color produced by mixing inks into the color you want in your project. It uses different ink for each color created based on Pantone Matching System (PMS) colors. Each Pantone color is assigned a different number and name.
Printers in different locations can use the name and number to identify Pantone colors. When using spot colors in printing, the colors produced are accurate to their design because they are assigned the Pantone number.
The purpose of a spot color is to enable printers to guarantee that a particular color will be printed in a particular shade. This is necessary when printers need to produce a specific color in a large printing job.