The document discusses the concept of volume in visual terms. It defines volume as the space taken up by an object or substance within an enclosed container or vessel. Volume assumes its characteristics from the arrangement of mass and form within the space. Volumes are three-dimensional, having length, width, and depth. They can be suggested two-dimensionally using drawing techniques like isometrics or perspective. Like other visual elements, volumes can carry psychological or emotional associations depending on their characteristics. The document provides several examples of different types of volumes and encourages imagining how they might feel.