Esthetics is the American spelling of aesthetics. It has two lives, and they do not feel the same. First, it is the study of beauty and art: why we call a painting beautiful, and how art works on us. That is a subject name, like mathematics — the s at the end does not mean “many small beautiful things.” Art students and people who write about art use this sense. Second, in American English especially, esthetics is also the beauty trade: skin care, facials, salon work. A person who does this may be called an esthetician. British English does not lean on this second sense as much; people there more often say beauty therapy or something like it. Though actually, the school subject and the salon are cousins — both care about how things look — but an art class and a facial are not the same world. If you only learn the salon sense, you will be lost in an art class, and the other way round. This is not a spelling of aesthete (a person). In casual talk, many people never say the word at all; they say art, beauty, or 美容.

美學；美式也指美容業。台灣課堂多說「美學」，沙龍說「美容」