In the 20th century and throughout the history of the discipline, drawing has been the dominant means of architectural communication and is considered to be the “language” Entries A–F 103 of architecture. Through drawings, an architect can record new ideas, concepts, and even visionary projects in addition to projects intended for construction. To facilitate this communication, a number of drawing conventions have evolved. Orthographic Projections The most commonly used projective drawing in 20th-century architectural practice is the orthographic projection. The primary orthographic projections are plan, section, and elevation views in which the observer’s line of sight is perpendicular to both the drawing plane and the surfaces of the building viewed and in which the drawing surface is parallel to the principal surfaces of the building. The floor plan and building section are both sections, or cuts. The floor plan, a sectional view looking down after a horizontal plane, cut through th...