The International Style is the name of a major architectural style that is said to have emerged in the 1920s and 1930s, the formative decades of modern architecture, as first defined by Americans Henry-Russell Hitchcock and Philip Johnson in 1932, with an emphasis more on architectural style, form and aesthetics than the social aspects of the modern movement as emphasised in Europe. The term "International Style" first came into use via a 1932 exhibition curated by Hitchcock and Johnson, Modern Architecture: International Exhibition, which declared and labelled the architecture of the early 20th century as the "International Style". The most common characteristics of International Style buildings are said to be: i. rectilinear forms; ii. light, taut plane surfaces that have been completely stripped of applied ornamentation and decoration; iii. open interior spaces; iv. a visually weightless quality engendered by the use of cantilever construction. Glass and steel, in combination with usually less visible reinforced concrete, are the characteristic materials of the construction.