The document discusses the element of line in visual art. It begins by defining different types of lines such as outline, contour, and implied lines. It explores the qualities lines can possess like direction, thickness, and movement. Specific artworks are analyzed to show examples of different line usages, including the expressive lines in Van Gogh's The Starry Night and the rigid grid structure in Sol LeWitt's wall drawings. The document also examines how artists' styles and techniques with lines change over time, such as Hung Liu incorporating drips in her work.