Conceptual art is art in which the concept(s) or idea(s) involved in the work take precedence over traditional aesthetic and material concerns. Many of the works, sometimes called installations, of the artist Sol LeWitt may be constructed by anyone simply by following a set of written instructions. This method was fundamental to LeWitt's definition of Conceptual art, one of the first to appear in print:

Tony Godfrey, author of Conceptual Art (Art & Ideas) (1998), asserts that conceptual art questions the nature of art, a notion that Joseph Kosuth elevated to a definition of art itself in his seminal, early manifesto of conceptual art, "Art after Philosophy" (1969). The notion that art should examine its own nature was already a potent aspect of (the influential art critic) Clement Greenberg's vision of Modern art during the 1950s. With the emergence of an exclusively language-based art in the 1960s, however, conceptual artists such as Joseph Kosuth, Lawrence Weiner and the English Art & Language group began a far more radical interrogation of art than was previously possible (see below). One of the first and most important things they questioned was the common assumption that the role of the artist was to create special kinds of material objects.

Yoko Ono (オノ・ヨーコ（小野 洋子）, Ono Yōko^?, born February 18, 1933) is a Japanese artist, author, and peace activist, known for her work in avant-garde art, music and filmmaking as well as her marriage to John Lennon. Ono brought feminism to the forefront in her music which prefigured New Wave music and is known for her philanthropic contributions to the arts, peace and AIDS outreach programs.

Yoko Ono was born in Tokyo in 1933 to mother Isoko Ono, the great-granddaughter of Zenjiro Yasuda of the Yasuda banking family, and to father Yeisuke Ono, a banker and one-time classical pianist who was a descendant of an Emperor of Japan. The name "Yoko" means "ocean child". Two weeks before she was born, her father was transferred to San Francisco by his employer, the Yokohama Specie Bank. The rest of the family followed soon after and Yoko met her father when she was two. Her younger brother Keisuke was born in December 1936. In 1937, her father was transferred back to Japan and Ono was enrolled at Tokyo's Gakushuin (also known as the Peers School), one of the most exclusive schools in Japan.