A type of technical drawing produced by architects to describe the projection of a vertical plane cut through space, and the projection in elevation of information lying beyond the cut plane. Sections generally delineate and describe the relationship of levels within a building, however a section could also show the vertical organisation and relationships of an urban area, the vertical relationship of a building to its context, spatial qualities within a room, or technical production information in a construction drawing.

The most basic convention of a section drawing, is that they consist of three groups of linetype: the cut line, the elevation line, and the hidden line. The distinction of these lines describes the location of the information in space - either co-planar with the cut, in front of the cut, or behind the cut. Conventionally cut lines are distinguished by a bold stroke, elevation lines by a light stroke, and hidden lines by a dashed stroke.

Often the section is used as a secondary tool, while the plan drawing is the main descriptor and design generator. In this case architects use the section to show information that cannot be easily read in plan - such as the form of a roof or ceiling, and the relative heights and levels within a building.