Line: an element of art used to define shape, contours, and outlines. It can also suggest mass and volume. It may be a continuous mark made on a surface with a pointed tool, or it may be implied by the edges of shapes and forms.
Wassily Kandinsky - "Throughgoing Line" 1923 (oil on canvas)
Outlines - lines made by the edge of an object or its silhouette Contour Lines - Lines that describe the shape of an object and the interior detail.
Calligraphic Lines - Greek word meaning "beautiful writing". Precise, elegant handwriting or lettering done by hand. Also artwork that has flowing lines like an elegant handwriting.
Sketch Lines - Lines that captures the appearance of an object or impression of a place.
Gesture Lines - Lines that are energetic and catches the movement and gestures of an active figure.
Implied Line - Lines that are not actually drawn but created by a group of objects seen from a distance, the direction an object is pointing to, or the direction a person is looking at.