Art is a diverse range of human activities in creating visual, auditory or performing artifacts – artworks, expressing the author's imaginative or technical skill, intended to be appreciated for their beauty or emotional power. In their most general form these activities include the production of works of art, the criticism of art, the study of the history of art, and the aesthetic dissemination of art. There is no universally accepted definition of art. Although commonly used to describe something of beauty, or a skill which produces an aesthetic result, there is no clear line in principle between (say) a unique piece of handmade sculpture, and a mass-produced but visually attractive item. We might say that art requires thought - some kind of creative impulse - but this raises more questions: for example, how much thought is required? If someone flings paint at a canvas, hoping by this action to create a work of art, does the result automatically constitute art? Contemporary definitions are of two main sorts. One distinctively modern, conventionalist, sort of definition focuses on art's institutional features, emphasizing the way art changes over time, modern works that appear to break radically with all traditional art, and the relational properties of artworks that depend on works' relations to art history, art genres, etc. The less conventionalist sort of contemporary definition makes use of a broader, more traditional concept of aesthetic properties that includes more than art-relational ones, and focuses on art's pan-cultural and trans-historical characteristics.