The appropriate use of color in Visualization is a very important subject. The choice of the proper color scale to use with a particular data set is not just a matter of choosing the prettiest representation. Throughout the years researchers have studied this subject and managed to propose guidelines which help users along the process of color scale selection. This article presents a brief overview on the subject focusing on the desired properties for color scales, the guidelines that should drive their choice, the advantages of applying those guidelines, the experimental research work on the field, and the tools proposed to help non-expert users.