the notation of line or straight line was introduced by ancient mathematicians to represent straight object with negligible width and depth.
types of lines
straight line
curved line
horizontal lines
vertical lines
slanting lines
Contour lines
dividing lines
decoration lines
gesture lines

contour lines- are used to define edges. the creat boundaries around on object.

dividing lines- also define edges, but what distinguishes them drom counter lines is they divided space. the lines between culoms of txt.

decoration lines- used to embellish an object. cross hatching is an example of using decoration lines to add shading and form to an object.

gesture line- are quick and rough continous line use to capture form and movement. they are generally used when studying the shape and motion of the human form.