A section is a slice through an object, either vertically or horizontally. Its purpose is to show how an item is put together. Sections are common drawings in architectural drafting. When a section is made through just part of an object, it’s called a detail. See this drawing in my book, Drafting and Visual Presentation for Interior Designers, and read more about sections in it or my other book, Architectural Drafting for Interior Designers .
Drafting, Modeling and 3D Printing with Lydia Sloan Cline
Hand drafting for Interior Design, SketchUp, Autodesk 123D and MakerBot