Final answer:
An actual line is a continuous mark that is physically present and visible, contrasted with implied lines which are suggested rather than drawn. Organic lines, which are typically flowing and curvy, add a dynamic and expressive quality to art.
Step-by-step explanation:
A line that is a continuous mark is typically referred to as an actual line. This term defines a line that is physically present and can be seen. It contrasts with implied lines which are not actually drawn but are suggested through elements within the artwork, and thus the viewer can perceive them mentally. In terms of line quality, organic lines are those found in nature, which are often flowing and curving, while inorganic or geometric lines are usually straight or perfect curves like those found in geometry. For example, in Albrecht Dürer's prints, we can observe organic lines in the horses' manes and figurative hair, which contrast with the inorganic horizontal lines in the background. Line quality contributes significantly to the visual sensation and character of an artwork, with organic lines often bringing a dynamic and expressive flavor to the piece.