This article focuses on the domain of aesthetics and various problems and issues associated with aesthetics. Aesthetics is the branch of philosophy devoted to conceptual and theoretical inquiry into art and aesthetic experience. This article offers first an outline of the structure of philosophical aesthetics as a whole, and then a selective sketch of the development of Anglo-American aesthetics over the past fifty years, focusing on five central topics: the concept of the aesthetic, the definition of art, the ontology of art, representation in art, and expression in art. The three foci of aesthetics are labeled as art, aesthetic property, and aesthetic experience.