Installation artworks (also sometimes described as ‘environments’) often occupy an entire room or gallery space that the spectator has to walk through in order to engage fully with the work of art. Some installations, however, are designed simply to be walked around and contemplated, or are so fragile that they can only be viewed from a doorway, or one end of a room. What makes installation art different from sculpture or other traditional art forms is that it is a complete unified experience, rather than a display of separate, individual artworks. The focus on how the viewer experiences the work and the desire to provide an intense experience for them is a dominant theme in installation art. As artist Ilya Kabakov said: "The main actor in the total installation, the main centre toward which everything is addressed, for which everything is intended, is the viewer."