Type of modern art in which the idea or ideas that a work expresses are considered its essential point, with its visual appearance being of secondary (often negligible) importance. Conceptual art challenges the validity of traditional art, and claims that the materials used and the product of the process are unnecessary. As the idea or ideas are of prime significance, conceptual art is made up of information, including perhaps a written proposal, photographs, documents, and maps. The term has come to encompass all art forms outside traditional painting or sculpture, such as video art and performance art.
Conceptual art is a highly controversial art form. Its supporters think it marks a significant expansion of the boundaries of art, which were previously growing increasingly commercialized. However, its detractors believe that it is trite, banal, and pretentious.
The roots of conceptual art can be traced back to Marcel Duchamp, who from the second decade of the 20th century produced various iconoclastic pieces in which he questioned the traditional values of the art world. However, conceptual art did not acquire a name or become a recognized movement until the late 1960s. It then rapidly became widespread, flourishing at the same time as other movements, such as Arte Povera, Land art, and performance art, that tried to escape from the commercialization of the art world by eliminating or underplaying the role of a collectable art "object". As with those other genres, works of conceptual art, and their documentation, have in fact proved commercially valuable. Conceptual art had passed its period of peak popularity by the mid 1970s, but there was a strong revival of interest in it in the 1980s. The term neo-conceptual is sometimes applied to work of this later phase.
Exponents of conceptual art sometimes try to deal with serious political and social issues, but often they are engaged in an abstruse analysis of the nature of art. Their media take a great variety of forms, including diagrams, photographs, video tapes, sets of instructions, and so on. Some conceptual works do not have any physical existence in the normal sense. In 1969, for example, the US artist Robert Barry created a work called Telepathic Piece, which consisted of a statement that during an exhibition he would "try to communicate telepathically a work of art, the nature of which is a series of thoughts that are not applicable to language or image".