Art in which the ideas presented in the work are more important than its physical form or style. Conceptual art emerged as an art movement in the 1960s. Prominent conceptual artists include Joseph Kosuth, Sol LeWitt, Lawrence Weiner, On Kawara, Piero Manzoni, Robert Barry and John Baldessari. Web resources here and here.
Robert Rauschenberg. Portrait of Iris Clert. 1961. Ahrenberg Collection, Switzerland.