In architecture and interior design, a section is a 2D drawing that shows the internal view of a building or structure as if it were cut through a vertical plane. Sections are one of the key types of architectural drawings, along with plans and elevations, and are used to communicate the internal organization, construction, and spatial relationships of a building.

A section typically shows the floors, walls, roofs, and other structural elements of a building, as well as the rooms, spaces, and circulation areas that make up the interior. Sections are drawn to scale, using standard architectural scales and conventions, and may include dimensions, annotations, and graphic symbols to indicate materials, finishes, and other important details.

Sections serve several important purposes in the design and construction process:

1. Spatial Relationships: Sections are used to explore and communicate the vertical relationships between different levels and spaces in a building, such as the height of ceilings, the depth of foundations, and the connection between floors.

2. Structural Design: Sections are used to show the structural system of a building, including the size, shape, and materials of walls, columns, beams, and foundations. They provide a clear and detailed view of how the building is supported and stabilized.

3. Building Systems Integration: Sections are used to coordinate the integration of different building systems, such as HVAC, plumbing, and electrical, within the overall structure and layout of the building. They help to ensure that these systems are properly sized, located, and connected.

4. Construction Documentation: Sections are a key part of the construction documentation package, providing detailed information for contractors, subcontractors, and suppliers. They are used to specify the materials, dimensions, and assembly details of different building components.

5. Code Compliance: Sections are used to demonstrate compliance with building codes and regulations, such as fire safety, accessibility, and energy efficiency requirements. They provide a clear and verifiable record of the building's internal organization and construction.

There are different types of sections that can be used depending on the purpose and level of detail required, such as:

• Full Sections: Show the entire building from top to bottom, including all floors, walls, and roofs.

• Partial Sections: Show a specific part or aspect of the building, such as a stairwell, an atrium, or a facade detail.

• Wall Sections: Show a detailed view of the layers and components of a specific wall assembly, including insulation, cladding, and finishes.

• Detail Sections: Show a highly detailed view of a specific building component or connection, such as a window sill, a roofing system, or a foundation detail.

With the advent of computer-aided design (CAD) and building information modeling (BIM) tools, sections can now be generated automatically from 3D models, allowing for greater accuracy, coordination, and visualization in the design and construction process. However, the ability to create and interpret hand-drawn sections remains an important skill for architects and designers, as it allows for greater flexibility, creativity, and communication in the design process.