The term “installation art” developed in the 1970’s and refers to art designed for a particular space, usually an indoor space, and is usually temporary. Installation art can incorporate sculpture, video, performance, and mixed media. In a way, installation art conceives of a museum or gallery exhibition space as a work of art in and of itself, and viewer interaction with the space is at the core of the form. Installations often have specific themes and messages and can be designed by a single artist or a group. Artists who have created notable installations include Rachel Whiteread, Ai Weiwei, and Jenny Holzer. The artist Suvan Geer even includes elements of smell in her installation work. (For more examples, see the chapter on “Contemporary Art 1960s to Present.”)