Art is an activity, the product of that activity or the idea of it, which deliberately addresses the senses, emotions, intuitions and intellect. However, there would be 10 kinds of arts, so established since the end of the 20th century. We find architecture as the first art, then sculpture, visual arts, music, literature, performing arts, cinema, media arts, comics and, finally, digital art as the 10th art. A classification that would thus help to determine and situate the art forms that have existed until now. Art is not nature, science, craft. Art is us, Science is you. Art is different from science, it even uses science. We consider the term "art" in opposition to nature "conceived as a power producing without reflection", and to science "conceived as pure knowledge independent of applications". One wonders what Art is. This Book proposes to elucidate the generalities, the classification of Art and to give a view on nature, science and craft.