The line is a continuous longitudinal sequence of points. Lines in art may be visible, such as those drawn, or suggested. The suggested lines are those that are not in the work in an explicit material way, but their direction is perceived in the set. The line is part of the seven basic elements of visual art, which are color, form, line, shape, space, texture, and value. Those elements of art are the building blocks used by artists to create a work of art.

Line quality is also called line weight and simply put, refers to the thickness or thinness of the line.  Lines may become wider or thicker in areas where the object itself is thicker.  Or lines may become thicker to help indicate a light source.  Lines in areas of shadow may be thicker.  By varying line quality (weight) you add variety to your work.  Take a look at the apples below.  Notice how varying the line quality in the drawing on the right, makes the apple appear to have form.