AMBIGUITY
The Mountain, Balthus. Photo: © Alfonso Vicente / Alamy
APPROPRIATION
Andy Warhol Flowers, Richard Pettibone. Photo: © Presselect / Alamy
AUTHENTICITY AND OUTSIDER ART
Henry Darger image courtesy of the American Folk Art Museum.
COLLAGE AND ASSEMBLAGE
Man with Pipe, Georges Braque. Photo: © SuperStock / Alamy
Specific Hungers, Kathy Bruce. © The artist. Photo courtesy the artist.
Dream, Reginald Case. Photo courtesy of Bonnie Case.
COLOR AS LIMIT
The Zorn Palette. Image and photograph courtesy of Michael Lynn Adams.
CONCEPTUAL ART
No Secret Painting XI. Art and Language. © The artist. Photo courtesy of Lisson Gallery, London.
CONSISTENCY OF VISUAL LANGUAGE
Idyll, Francis Picabia. Photo: © ACTIVE MUSEUM / Alamy
DISTORTION
Fang Mask, Gabon. Photo. Marie-Lang Nguyen. Released into public domain.
EROTIC ART
Kiss Painting, Betty Tompkins. © The artist. Photo courtesy of Galerie Rodolphe Janssen, Brussels. Private Collection.
EXPRESSION IN THE ABSTRACT
Rosy-Fingered Dawn at Louse Point, Willem de Kooning. Photo: © Peter van Evert / Alamy
GENDER
Abundance: Shoes, Claudia DeMonte. © The artist. Photo courtesy of June Kelly Gallery, New York.
INSTALLATION
Installation at the Rose Art Gallery, Brandeis University. Judy Pfaff. Photo: Boston Globe / Getty Images
INTERACTIVE ART
The Gift, Birthe Blauth. © The artist. Photo courtesy of the artist and 532 Gallery Thomas Jaeckel, New York.
JUXTAPOSITION
Son of Man, René Magritte. © Heritage Image Partnership Ltd / Alamy
KINETIC ART
Trigger Fish, David Beck. © The artist. Photo courtesy of Hackett Mill Gallery, San Francisco, CA.
LAND ART
Mapping Arcadia, Cazenovia and the Topography of Place, Alastair Noble. Photos courtesy of the artist.
LAYERS
Yangon, Joan Thorne. © The artist. Photo courtesy of Sideshow Gallery, New York, NY.
MATERIALS AS ART
Kitchen, Liza Lou. © The artist. Collection of the Whitney Museum of American Art, New York. Photo by Bruce Osborn provided by the artist.
Untitled, Donald Judd. Photo: © Presselect / Alamy
OP ART
Zephyr, Bridget Riley. Photo: © Daily Mail/Rex / Alamy.
Vassarely paintings at auction. Photo: © Press2000 / Alamy
PERFORMANCE ART
BEBECHY, Krzysztof Zarebski. Courtesy of the artist. Photo: Zosia Zeleska-Bobrowski.
Zero Gravity, Nadja Verena Marcin. Courtesy of the artist. Photo: Violetta D’Agata. Sponsored by WARP & Aurora Aerospace.
POLITICS AND POLEMICS
F-111, James Rosenquist. Photo: © Peter Horree / Alamy
PROCESS AS MEANING
Autumn Rhythm Number 30, Jackson Pollock. Photo: © Peter Horree / Alamy
Untitled, Robert Morris. Image courtesy ARS.
REPETITION
Nine Jackies, Andy Warhol. © Peter Horree / Alamy
RHYTHM
Dassin, Melissa Meyer. © The artist. Photo courtesy of Lennon, Weinberg Gallery, New York. Private Collection.
SHAPE
Tilt, Don Voisine. © The artist. Photo courtesy of McKenzie Fine Art, New York.
SHOCK ART
Piss Christ, Andres Serrano. © The artist. Photo Bridgeman Archive. Many thanks to the artist for waiving his rights fee.
SUCCESSIVE APPROXIMATION
Portrait of Annette, Alberto Giacometti. Photo: © Peter Horree / Alamy
SURREALISM
The Antipape, Max Ernst. Photo: © Heritage Image Partnership Ltd / Alamy
SYMBOLS
Tuttomondo Wall Painting (detail), Keith Haring. Photo: © age fotostock / Alamy
TEMPORARY ART
New Geology #2, Steven Siegel. Photo courtesy of Marlborough Gallery, New York, NY.
TEXTURE
Dein aschenes Haar Sulamith, Anselm Kiefer. Photo: © Peter Horree / Alamy
UNDERPAINTING
Demonstration, Nanette Fluhr. Photos courtesy of the artist.
VIDEO ART
Self-Portrait, Nam June Paik. Photo: AFP/Getty Images