What is 4-color process printing?

4-color process printing is the use of four unique ink colors (cyan, magenta, yellow, black) using sophisticated screens to produce full color photographs like printing. It can also closely reproduce PMS spot colors enabling the ability to produce a very colorfully printing product with the expense of additional spot colors. Close is the best you can achieve with PMS colors, as it is impossible to exactly match PMS spot colors with 4-color process. This would be its biggest drawback from using individually printed spot colors.