Developments in the art world seem always to keep one step ahead of philosophical attempts to characterize the nature and value of art. A pessimist may conclude that theories of art are doomed to failure. But those more optimistic about the prospects for progress in philosophy may retort that avant-garde art does philosophers a great service. It helps to ensure that generalizations are true, conceptual analyses are adequate, and that the theories in which generalizations and conceptual analyses are embedded enjoy maximal explanatory power. Arguably the most important engine for artistic innovation in recent years has been the new information technologies, especially multimedia, hypertext, and the Internet. These technologies have made possible not only new means for distributing art but also new kinds of art, including "interactive art." While interactive art raises many interesting questions that a full account of it must address, a good start can be made by examining its ontology. Indeed, most questions about interactive art cannot be properly addressed absent a rough outline of its ontology. Moreover, it is not obvious what should be said about the ontology of interactive art. David Saltz has argued that the type-token distinction (which is widely taken to account for the relationship between works of literature, music, theatre, and drama on one hand and instances or performances of them on the other) does not apply to interactive artworks. The writer argues to the contrary that interactive artworks are types whose tokens are produced by interaction with them. Showing that this is the case will, however, require a new or, at least, expanded account of how artwork types can be instantiated. The resulting argument, if sound, has implications for the ontology of art as a whole and also touches on the aesthetics of interactive art. The purpose of an ontology of art is to provide a framework of concepts used to account for facts about the nature and appreciation of art: the author views this as an important constraint on ontologies of art. By examining its ontology, it should be possible to learn something about the character and value of interactive art. (Contains 24 notes.)