Allan Kaprow was an American painter

Painting

Painting is the practice of applying paint, pigment, color or other medium to a surface . The application of the medium is commonly applied to the base with a brush but other objects can be used. In art, the term painting describes both the act and the result of the action. However, painting is...

, assemblagist

Assemblage (art)

Assemblage is an artistic process. In the visual arts, it consists of making three-dimensional or two-dimensional artistic compositions by putting together found objects...

 and a pioneer in establishing the concepts of performance art

Performance art

In art, performance art is a performance presented to an audience, traditionally interdisciplinary. Performance may be either scripted or unscripted, random or carefully orchestrated; spontaneous or otherwise carefully planned with or without audience participation. The performance can be live or...

. He helped to develop the "Environment

Installation art

Installation art describes an artistic genre of three-dimensional works that are often site-specific and designed to transform the perception of a space. Generally, the term is applied to interior spaces, whereas exterior interventions are often called Land art; however, the boundaries between...

" and "Happening

Happening

A happening is a performance, event or situation meant to be considered art, usually as performance art. Happenings take place anywhere , are often multi-disciplinary, with a nonlinear narrative and the active participation of the audience...

" in the late 1950s and 1960s, as well as their theory. His Happenings - some 200 of them - evolved over the years. Eventually Kaprow shifted his practice into what he called "Activities", intimately-scaled pieces for one or several players, devoted to the study of normal human activity in a way congruent to ordinary life.