Architectural comprehension as a field deals with representation as a synthesis of varied efforts —constructive, compositional, spatial, and technical qualities— which are then articulated in the constructed building. For this purpose, it is essential to think about the graphic representation that presupposes all these efforts, since it is both a procedure and a product of architectural design.
In this sense, it can be understood that architectural debate throughout history, at different periods of time, was translated into drawings. The drawing exercise refers directly to the discourse behind the work of architects of all schools, movements, and periods. Therefore, in addition to the aesthetic, formal and constructive choices, representation options are also a topic of debate among professionals and theoreticians in the field.
In a text on contemporary design strategies in São Paulo, Mario Biselli and Ana Gabriela Godinho Lima say:
As an intellectual and cultural product, architecture has much to say and contribute; it is an activity that calls for and mobilizes a kind of synthetic, syncretic and dynamic intelligence. 
Floor plans, sections, and elevations are a traditional representational triad that architects use in their projects. However, it is possible to infer that the section is, and historically has been, the most interesting drawing since it is understood as a representation of the architectural design itself.
It is in the section that the conceptual design becomes virtually real. It illustrates the vertical dimension of the drawing, that is, the dimension that relates to the user scale with proportional notions. In Manual of Section, Paul Lewis, Marc Tsutumaki, and David J. Lewis state that "the section is the place where space, form, and material meet with human experience."  In addition, it is also the representative tool that places the project in dialogue with its context, and with the topography of the space that it occupies. It is even subject to the limitations of representation, like any drawing, it can simultaneously synthesize the formal, programmatic, constructive, compositional, spatial, and organizational issues of the project.
The section is also critical in the debate that allows contemporary architecture on a path of overcoming modern precepts which, based on the 5 points of Le Corbusier, considered the "free plan" as the defining organizational principal of architecture. Rem Koolhaas launches from that, in his project for the 1989 National Library of France competition, with the idea of the "free section."
A very notable and current example of this procedure is the Moreira Salles Institute in São Paulo, Brazil. The metal structure that supports a translucent double-layer glass skin is organized vertically. For instance, with the escalators being a principal part of the project.
Although common in recent works, the vertical or sectional approach to design has been used historically. Archigram's 1960s conceptual proposals use this graphical tool to create diagrams and drawings that express infrastructural innovations for global projects that oppose the proposals from Europe.
This also occurred in Latin America, with Argentinean architect Clorindo Testa's National Library in Buenos Aires and the Bank of London. Both projects present sections of great expressiveness that reveal the rationale involved in his works.
In Brazil, Angelo Bucci is perhaps an architect whose work is most reflected in sections. The Carapicuíba House, designed in partnership with Alvaro Puntoni, reveals vertical relations that emphasize the importance of the section for the design. In dialogue with a terrain of great inclination, the house and office are organized in a distribution that goes with the verticality of the lot, an aspect reinforced by the representation in the drawings.
Another example is Bucci's House in Ubatuba, which uses a topographic determinant to use verticality as the starting point of the project. Located on a hillside, the house is supported by three large pillars that function as the organizational axes of the environments, arranged in volumes connected by elements of vertical circulation.
-  Estratégias contemporâneas de projeto na cidade de São Paulo: Instituto Moreira Salles e Sesc 24 de Maio. Mario Biselli e Ana Gabriela Godinho Lima, 2018. Available in Vitruvius.
-  Tradução livre retirada de Os limites do corte: ensaio sobre representação gráfica. Beatriz Hoyos, 2016
Editor's Note: This article was originally published on November 30, 2019, and updated on October 24, 2020.