The document discusses contour line drawing and its importance for developing drawing skills. It defines contour drawing as lines that define the edges of a subject, giving it shape and volume. It explains that edges are always shared boundaries where two parts or things meet. Regular practice of contour line drawing can help sharpen one's perceptual skills, especially the perception of edges. The document recommends keeping a visual diary or sketchbook to record observations, experiment with ideas, and make studies for future reference.