The categories used to describe skin types have changed little over the last century, whereas the skin care product market has undergone rapid innovation and exponential growth. There are four basic dichotomies or parameters that have recently been introduced in the Baumann Skin Type Indicator (BSTI) that more accurately characterize skin types. By evaluating skin according to these parameters—dry or oily, sensitive or resistant, pigmented or nonpigmented, and wrinkled or unwrinkled—and thus differentiating among the 16 permutations of possible skin types, consumers can more easily identify the most suitable topical treatments for their skin. This article describes the four parameters that make up the BSTI, focusing on basic science and defining characteristics and summarizing the 16 skin-type variations.