They can be realized as edges or boundaries to objects as well as contours to shapes and forms. A line can lead the reader's eye as well as provide movement and energy to anycomposition. When used properly, a line can improve readability, immediacy, and the ultimate meaning of any visual message.
We are taught "a line is the shortest distance between two points." While this fact is true, we have never been taught to appreciate the other inherent characteristics and qualities of a line. Since man felt the need to visually communicate his day-to-day experiences bymaking marks on cave walls, he has unconsciously relied upon line. This fact is evident in cave paintings in southern France, burial messages in Egyptian hieroglyphics, inscriptions on Roman tribunal arches, and medieval crests adorning castle walls. Line has always been a fundamental element of our visual communications palette.
In reexamining these historical references, we can further identify the many func-tions that man has given to line.
Character and Meaning
A line is composed of a number of points located next to one another in one direction; the number of points can be infinite or there can be two endpoints—a beginning point and an endpoint—or a vector. Its path defines the quality and character of the resulting line. It can be straight, meander, or curve across itself or it can follow the precise arc of a circle segment. The end result gives specific character and meaning to each line.
A line is elemental in visual communications. It is also a fundamental element of visual geometry. Without it, the circle, square, and triangle would not exist, nor could we visually represent them. As an elemental geometric form, a line always has length, but never breadth. When this proportional relationship occurs, a line inevitably becomes a plane or surface.
The primary function of a line in visual communications is to connect or separate other elements in a composition. A line's inherent nature is directional. When it is articulated as a smooth gesture, the eye follows it in an easy and unconscious manner; when it is rough or irregular, it impedes movement, thereby slowing the eye's connection with it.Lines create boundaries and ultimately define shape and form. They are inherently dynamic gestures as opposed to points that are always static. Lines communicate movement because they move in two directions.
Man created line as the simplest means to visually communicate. We see lines as boundaries in objects and are initially taught to draw lines as a way to convey or communicate naïve shapes and forms.
Tone and Message
A line communicates division, organization, emphasis, sequence, and hierarchy. These inherent functions can change in tone and message through the tool used to articulate a line. Lines are expressive. They can be long, short, thick, thin, smooth, or irregular and can convey a wide range of emotions. A straight line is mechanical and cold; a curvilinear line is natural and approachable; a thin line is soft and restrained; a bold line communicates strength and power.
If a line is drawn with a brush, it conveys a more fluid and undisciplined message as opposed to a line created with a mechanical pen that conveys precision and a disciplined message. Another aspect of line quality is determined by the tool that makes it; for example, the sketched quality of a charcoal pencil line, the precision of a line drawn with a digital pen tool, or the organic quality of a line brushed with ink. Again, history confirms this to be true. From the naïve nature of a line drawn by a hand's finger or a branch from a tree to a metal scribe or a calligraphic pen nib, the communicative nature of the line has evolved over time at the same pace as man's reliance on different tools and technologies.
The orientation and position of a line can also further influence a visual message. A horizontal line is calm, quiet, and serene; a vertical line communicates strength, height, and aspiration. Vertical lines appear more active and communicate a more powerful and immediate message than a series of horizontal lines. Diagonal lines are much more suggestive, energetic, and dynamic. While we have always been told to "color within the lines," we should consider that lines can be realized in a variety of different graphic forms. They can be straight, curvilinear, thin, thick, solid, and dotted. Multiple lines, whether parallel or juxtaposed at right angles, create texture, movement, tension, pattern, tone, value, perspective, and structure.
The graphical articulation of a line also impacts its presence, subtle or obvious, on any given surface. Shaded lines recede as they change from thick to thin, creating a subtle illusion of space. The thicker the line, the more it comes forward or advances.
Another way to think of line is as an edge. When it is given this function, it allows the eye to perceive an object from its background. We also immediately understand line as edge when a horizontal line distinguishes land from sea or land from sky. A linear edge can also exist along the side of any straight or curved shape or as the result of shapes sharing the same edge.
A line can also be implied, meaning it occurs as the result of an alignment of shapes, edges, or even points. Implying the existence of a line in that way can be very engaging for the viewer. Implying lines also activates the compositional space.
The Quality of a Line
Lines have a variety of functions in visual communications. They can serve as the contour of an object or human figure or exist purely to serve themselves as elements used to separate information, lead the eye in a particular direction, or imply alignment. Lines can also become textures or patterns. The quality of a line can communicate the nature of what is being described; for example, delicate, precise, angular, architectural, chemical, anatomical, fluid, or awkward.
One of the most prevalent uses of line is in print material, such as newspapers, magazines, publications, and websites. Here, lines are used to organize information,separate and emphasize content, and direct the eye to specific areas of interest. In all of these situations, line is used primarily to improve readability, allow easy access to information, and reinforce the immediacy of any visual message.