We all know what design elements are, whether we can name them outright or not. We are all implicitly aware of them. From the moment we are able to pick up a piece of chalk or a crayon, we can make a point, a spot, a mark.

GDPE diagrams point 01

Above is a dot I drew. Yay! As I make clear above, a dot is a type of point. Formally speaking, however, a point in space is less a visual concept and really more of an abstract, geometric notion. Euclid began his Elements with the following definition of a point:

Euclid's Definitions, from The First Six Books of the Elements of Euclid, by Oliver Byrne (1847)

Therefore, geometrically speaking, points have zero dimension, area, borders, or boundaries... all that defines them are their positions in space (thanks to Descartes). In the tangible world, however, one can make a dot on a piece of paper, as in my example at the top. Though this dot has slight dimensions, we really only interpret it as a point because of the principle of scale (which we’ll get to…). Increase the scale of the point, and you can see it is really a shape or form (and an odd one at that):

bruh, you need to get that checked out by a doctor...
That image above is an organic shape…but we initially interpreted it as a point due to its tiny scale. Scaled-down relative to the composition format or canvas, and it becomes something singular. But scale is only one attribute that defines points. 

The Vanishing Point

Joseph MW Turner Tracing of a Perspective Construction of a House c.1810, (from The Tate Collection)

Not all points used by artists and designers are visible. In fact, I'd wager that most are not. For example, the vanishing point – a staple of linear perspective drawing since at least the time of Brunelleschi (read more about that here) – is an abstract "point at which receding parallel lines viewed in perspective appear to converge (OED)." We can't see the vanishing points in a composition made with perspective in mind, but we know they're there because the angles of the elements in the composition tend towards them. 

Focal Points

Here's where it gets a little tricky. A focal point is also a type of point, one that our eyes are drawn to for a number of reasons. Contrasts of scale, apparent mass, color, positioning, and other attributes can imply various focal points in a composition (see here for a well-known example). This means that any element, regardless of scale, can be a point as well. Claude Monet's Impression, soleil levant (1872) makes great use of bright orange to create something slightly larger than a dot to create that painting's focal point. 

Below are some strategies for creating focal points.

Positioning (The Rule of Thirds)

The Rule of Thirds is a 'rule of thumb' for natural places of focus

The rational part of our brain might tell us that if you want an object or element to be the focus of a viewer's attention, just plop it right in the center of the frame. However, our instinctive brain doesn't work that way, and it turns out that, due to the way our brains instinctively scan our visual field for information, putting something right in the center of a composition makes it static: no motion, no visual interest...i.e. a lack of focus

In the images above, a portrait and a landscape format are trisected by two vertical and two horizontal, blue lines – into thirds. Where those blue lines intersect (circled in red), you will find natural focal point locations. Called The Rule of Thirds, Photographers use these focal points all the time to create visual interest and audience focus in their work. This isn't a hard and fast rule, and there isn't solid scientific evidence that these third zones are better than any other position, but there's no denying that the uneven spacing they enforce certainly helps content flow. Let's demonstrate with a picture of a sweet little girl!

On the left is the original photograph I took of my daughter Sloane, with her face in the center of the frame. She's super-cute, I admit. But the composition is not particularly interesting. On the right, I have placed our third lines, their intersections highlighted in red again. You can see that there isn't anything notable within those zones, and this is perhaps why this picture is kind of a yawn fest.

I cropped out some of the less interesting bits of the above original photograph and, seeing as faces are common focal points in any portrait, I make sure to place Sloane's cute little face within the top lefthand third zone. This composition is unambiguously about her, looking at toys, doing cute stuff. In other words, simply by cropping and positioning to a focal point and content flow, this composition now tells a little story. As Reinhardt famously said, "if it isn't worth a thousand words, the hell with it."

Scale, color, space, and the focal point

 

From Kate Greenaway's "A Apple Pie: An Old-Fashioned Alphabet Book" (1886)

This may seem obvious, but another way to create a focal point is with the contrast of scale and/or color. In the image above, taken from Kate Greenaway's 1886 children's illustrated nursery rhyme book A Apple Pie, the large uppercase A is the clear focal point, not only due to scale, but also due to its relatively saturated fill color and black outline. Also used here to great effect is negative space, which omits any background objects that might distract from the composition's main focus: The letter A, the words "Apple Pie," and the children dancing around a massive pie. Scale, color, and space are all used here to create a hierarchy of focal points.

 

GDPE diagrams lines 03

A line is classically defined as a connection between two points. I say "classically" because that is the way that classic geometry texts – specifically Euclid’s Thirteen Books of the Elements – defined it in definitions II and III:

Euclid's Definitions, from The First Six Books of the Elements of Euclid, by Oliver Byrne (1847)

Euclid was really defining a straight line. But artists and designers know that lines come in many different configurations: they can be curvy or wavy; they can be jagged and rough; they can demarcate a border between things, thereby separating them. But they can also connect things together. They can imply movement, draw our attention to things, or obscure things. Lines can be angry, sad, mysterious, direct, or implied by the alignment of other elements (a.k.a. implied lines).

straightlinedef

 
GDPE shape 100

You’ve definitely seen shapes and/or forms before, because they are everywhere. They are, in fact, an integral part of the conceptual framework that our brains use to identify objects. Forms can be free form, organic, naturalistic, geometric, lifelike, exciting, sad, aerodynamic, symbolic (think letters...), and many other things our brains assign them. But forms can also be entirely abstract, as the Greeks (Euclid included) used to think of them: perfect forms, existing only in abstract thought, from which all physical forms were (imperfectly) derived.

 

But even the most abstract shapes in the visual arts have some objective qualities. Case in point, Malevich’s referred to his 1915 piece Black Square as the "zero point of painting1," meaning that, other paint on canvas, it was nothing: just near-complete abstraction. Yet despite this high-minded rhetoric, it's chock full of objective elements, so it can still be referred to as a rectilinear shape that is dark black (value) and, at the time of this writing, has a crackled patina (texture).

Kazimir Malevich, "Black Square," 1915

Form

In two-dimensional design, forms are similar to shapes, in that they are actually two dimensional, but appear to be three dimensional, as seen below. If you've even created or seen a still life painting, you know what a form is!  

GDPE diagrams value 15

Value refers to the relative lightness (white) or darkness (black) of an element, and has considerable effect on the perceived weight, prominence, and position of that element. Differences in value create contrast, which is an excellent way to force a visual hierarchy (i.e. an order of importance). For example, in the below illustration, though the circle is subordinate to the other shapes in terms of scale and positioning, it nonetheless is the most prominent and ‘heavy’ object due to its dark values contrasting with the light values of the other shapes:

GDPE diagrams value 16

GDPE diagrams negative space 18

Often overlooked due to its frequent role as an absence of things is the element of space. But space is much more than an absence. It is properly defined as the area inside, outside, all around, above, and/or below the formal objects – or figures – in a composition. It can also be described as the ground behind one or more figures... and this is where it gets interesting.

Figure/Ground Relationships

 figure groundR figure groung@2x 100

In the above image, there are three square compositions, each containing an uppercase R (set in Didot). Each one demonstrates one of three kinds of figure/ground relationships: 

  • Stable: In the leftmost composition, it's pretty clear that there is a black R hovering on top of white ground, and can be described as having a stable figure/ground relationship. 
  • Reversible: In the middle composition, however, there is some tension as to what is figure and what is ground, even though we know it's just a closer cropping on a black R. This figure/ground relationship is said to be reversible because whether white or black is figure or ground can go either way.   
  • Ambiguous: in the rightmost composition, it's really never clear which in the figure and which is the ground. Both white and black have strong arguments for being the figure. Of course we can guess it's just another close cropping of the R, the relationship becomes ambiguous.

Figure/Ground Exercises

figure groundblack figures bw 100figure groundwhite figures bw 100

In the two images above, it's not clear which is the figure and which is the ground. It's also not clear where to look. As a result, and despite the dynamic movement of the diagonals shapes, the content flow throughout each image is fairly static. However, what if we changed that up a bit by adding some color to reveal what is the actual figure in each image:

figure groundblack figures color key 100figure groundwhite figures color key 100

By simply coloring two figures in each of the original images, I have achieved some content flow. The colors, in this case, identify which shapes are the figures (black on top, white on bottom), but they also provide strong focal points that create hierarchy. But there's still more we can do: the bottom image is still a little ambiguous: the colors could just be strips of color within black figures, hovering over a white background; or it could be white and colored strips hovering over a black background (which is actually how it was created). To fix this ambiguity, let's get rid of a few white figures and let the black dominate as the ground:

figure groundcleaned up white and colored shapes 100

Much better: now there is a healthy amount of negative space (black background), a dominant focal point (the magenta figure), a secondary focal point (the blue figure), and uneven spacing. All of these things help achieve successful content flow.

Here are more interesting uses of negative space and figure/ground reversals that I have found from the dank nether-regions of the web:

Depth and Space

Wait, we're not done yet... One important aspect of space is depth, and it refers to the appearance of a third axis – generally called the Z-axis in digital media – that originates from the viewer's point in space, out in to infinity along the viewer’s line of sight. Print, digital media, and film are all two dimensional, and therefore depth is merely an illusion. The onus to successfully represent depth rests squarely on the artist, designer, or filmmaker. Since at least the Renaissance, artists of all kinds have been struggling with this very challenge and, thankfully, we can reap the benefits. 

Below are just a few strategies for how artists and designers achieve the illusion of depth in 2D space:

Strategy 01: Representing Depth with Diminishing Scale, Diagonals, and Linear perspective

A painting of the Florence Baptistry, not by Brunelleschi, but perhaps close enough?

Linear perspective is perhaps the oldest strategy for representing the Z axis, and its discovery is credited to Filippo Brunelleschi, with his application of linear perspective in his painting of the Florentine Baptistry. As the story goes (according to Antonio Manetti), Brunelleschi painted an exact portrait of the Florentine Baptistry from the door of the Florence Cathedral (which he designed, and was currently in the process of constructing). The painting was so exact, he claimed, that one could superimpose his painting over the baptistry itself and they would match perfectly. He even purportedly designed an elaborate mirror system to do just this. 

A diagram of Filippo Brunelleschi's purported experiment

That said, Brunelleschi’s actual perspective paintings (which no longer exist...if they ever did) were not properly the first, as that credit belongs to one Ambrogio Lorenzetti, with his Presentation at the Temple, painted nearly a century prior in 1342. 

ambrogio lorenzetti 21 presentation in the temple
Ambrogio Lorenzetti, Presentation at the Temple (1342)

Indeed, a century later, architect Sebastiano Serlio would claim that linear perspective was well-known to the ancient world, and that 1st century Roman architect and general Marco Polio Vitruvius referred to it as scenographia. 

From Marco Pollo Vitrubius Ten Books on Architecture, by Gotardus da Ponte, 1521 

Despite this, it’s still not clear what exactly Brunelleschi intended with his pronouncement, other than to prove he ‘discovered’ something at a time where ‘discovering’ was all the rage. Here is how science historian David Wootton compares Brunelleschi and Lorenzetti:

It is evident that both paintings avoided the obvious method of demonstrating depth in a two-dimensional image, which is to show orthogonals, parallel lines running at right angles to the picture plane and converging on a vanishing point. The most straightforward example is a tiled floor.i Instead, both pictures must have used two-point perspective, where lines which are neither parallel to the picture plane nor at right angles to it converge on distance points to the left and right of the picture plane itself. If Brunelleschi wanted to experiment with depth of field, why not use a vanishing-point perspective, which would have been straightforward, and indeed familiar to him? Ambrogio Lorenzetti’s Annunciation of 1344, for example, uses a tiled floor and converging parallels to create a sense of depth of field. Lorenzetti had not mastered all the complexities of perspective construction – see how the back of Mary’s chair is higher than the front, and how the angel’s left foot is no further back than his right knee. But he did know how to make a tiled floor recede into the distance. If Brunelleschi was simply trying to create an impression of depth, he could have simply shown an interior with a tiled floor.

– David Wootton, “The Invention of Science: A New History of the Scientific Revolution.”  

Regardless, in much the same way the Columbus didn’t really 'discover' anything new upon landing in the Western Hemisphere, yet still became the 'Discoverer of the New World,’ so too did Brunelleschi become the 'discoverer' of perspective, as his process for creating this exact image would become the gold standard for forced, geometric perspective in Western art.

Strategy 02: Representing depth via value or atmospheric perspective

In addition to scale naturally diminishing as distance increases, so too does the visibility of objects. This is certainly due to a property possessed by all radiant energy (and gravity, as it happens), i.e. it naturally diminishes in luminance over distance – a fact which corresponds to the inverse square law.

A diagrammatic description of the Inverse square law (source)

But luminance is not the only property of light that is diminished over distance, as atmospheric conditions, such as smog, humidity, and just straight up air particles all absorb different wavelengths (read: colors) of light.

Therefore, as reflected light travels through our relatively thick atmosphere, both color and  brightness  appear to leach from – or modify within – the object we’re seeing. Many artists throughout history have been aware of this phenomenon, with argueably the most influential of responses coming from the Impressionists. But we can easily find an understanding of this in the work of Romantic period artists Joseph WM Turner and Eugène Delacroix half a century prior.  Look below at Turner’s lush Ancient Rome…(1839) or Delacroix's busy The Death of Sardanapalus (1827). How many layers of depth can you identify, and what techniques did they use to achieve the illusion of depth?* 

Joseph Mallord William Turner, "Ancient Rome; Agrippina Landing with the Ashes of Germanicus" (1839)
Eugene Delacroix, "The Death of Sardanapalus" (1827)
*Bonus points for identifying other ways Delacroix was a master of crearting the illusion of depth. Hint: look at the spaces in between figures... [this] may help.
But an artist who certainly broke interesting ground in his attempts to represent this phenomenon in his prints and etchings was Jacques Callot (1592 – 1635). In addition to perfecting other etching processes, he also substantially advanced the technique of 'stopping out' the acid etching process, producing areas of different etched depths, thereby resulting in areas of different amounts of ink on the same printing plate.  
Callot skillfully chose to 'stop out' those parts of the image that were to appear more distant, with closer foreground areas etched more deeply. When the etched plate was thereupon inked and pressed upon paper, ‘closer’ areas imprinted more darkly than  lighter, more ‘distant’ areas. For an example of this, check out the cheerful image below – produced in Callot's final year – and see if you can spot how many layers of depth there are:
Jaques Callot, "The Temptation of St Anthony" (1635)

Today we use a similar techniques to achieve the impression or illusion of depth in all types of media, thanks to innovators like Callot.

 

Strategy 03: Vertical placement

This one’s easy: our brains tend to perceive compositional elements closer to the top of the picture plane as being more distant, in addition to being higher in elevation, whereas those elements closer to the bottom appear to be closer. The ukiyo-e period of feudal Japan produced a high-water mark in vertically oriented landscape art, where we can see this technique used forcefully to create the illusion of depth.  Hiroshige's Kanōzan Mountain…, in particular, is a great example.

 

Andō Utagawa Hiroshige, "Kanōzan Mountain, Kazusa Province" (1858)

Make a quick note of the color distribution in Hiroshige's piece above. Notice how the perceived background of the image – the horizon line – is bathed in warm to cool gradient, whereas the foreground is progressively cooler as it appears to approach the viewer? This is distribution of warm and cool colors is actually a little counterintuitive, as you'll see in the fourth and final strategy below.   

Strategy 04: Suggesting Depth Through Color 

Lastly, and perhaps most importantly in regards to 2-dimensional media, we perceive warm colors as advancing towards us, where’s cool colors recede. This technique is used widely though art history, design, digital media, and filmmaking. In fact, pushing and pulling scene objects with color is one of the few tricks cinematographers have to make a 2D scene appear to have depth, which is why they chose their lighting colors very carefully.

Below is a landscape by German Expressionist Ernst Kirchner who, you can see, employs this cool/warm depth trick with aplomb, forcing an illusion of depth:

 

Ernst Ludwig Kirchner, landscape

 

Northern Expressionist Emil Nolde also uses this color trick in his work. See his two works below:

 

Emil Nolde, "Free Spirit," 1906

 Pieter Brueghel the Younger's The Crucifixion

 

This pushing and pulling of perceived distance via warm and cool colors has an important place in photography and cinematography as well. Turn on any film or TV episode and you will likely find this at work in various ways. Just for the sake of discussion, I have placed below various scenes from Lucrecia Martel’s 2017 super-excellent film Zama. This Argentinian film features intentionally overpacked scenes, with multiple layers of depth, to create an almost surreal, painterly atmosphere. 

 

 

 
In addition to being an element of design, color is also the whole entire body of theory called, not surprisingly, color theoryIt may seem odd to think about color be theoretical, but you have to understand this in the context of scientific pursuits going back at least to the middle ages with the publication of Kitāb al-Manāẓir (Book of Optics, 1021ce) by Arab scholar Ibn al-Haytham (Alhazen to us Westerners...). In this book, Alhazen laid out many discoveries about the nature of light and vision that we take for granted today, e.g. that light does not originate from the viewer's eye, then bounces off an object, and that it is, in fact, the other way around.

An image from Alhazen's "Book of Optics"
Alhazen remained the authority on light and color perception until Sir Isaac Newton's Opticks, wherein he essentially proved that colors are components of white light, sending aloft the first systematic volley in a massive discussion of color that has spanned continents, encompasses a multitude of definitions, concepts, systems, and design applications - enough to fill several hundred encyclopedias – and even continues even today. Color theory is concerned primarily with the properties of different wavelengths of light and how we perceive them. But it's also focused on the interaction of colors, i.e. how different combinations of colors can cause colors to change in the appearance of the constituent colors. However, there are three basic categories of color theory that are logical and useful in practical application: the color wheel, color harmony, and color relativity. 

The Color Wheel

 

Three color wheels - Harris, Today, Goethe

A color circle, based on red, yellow, and blue, is traditional in the field of art. Sir Isaac Newton developed the first circular diagram of colors in 1666. Since then, scientists and artists have studied and designed numerous variations of this concept. Differences of opinion about the validity of one format over another continue to provoke debate. In reality, any color circle or color wheel which presents a logically arranged sequence of pure hues has merit. Let's arbitrarily start with the work of Bauhaus artist and educator Johannes Itten and his 1961 piece entitled Farbkreis, a German word that translates literally to "color circle."

Johannes Itten, "Farbkreis," 1961
This piece reflects a more painterly understanding of colors — unsurprising, as Itten was himself a painter (in addition to a weaver). The classic primaries red, yellow, and blue are considered so because they cannot be made by mixing other pigment colors.

For painters and other types of artists and designers who manually mix pigments, Itten's system works well. But contemporary color theory is really more concerned with frequency interaction between differing hues, and how to represent colors accurately with different types of technology. These technologies fall into two distinct categories - screen-based and print-based - and the various colors systems used in each couldn't be more different.

Contemporary color wheel; Color systems; Color types
GDPE diagrams color systems 33Additive color systems arise from the direct mixture of different wavelengths (colors) of light. The primary colors in an additive system are generally red, green, and blue. Laptops, desktops, smartphones, tablets, televisions, portable gaming systems, smartwatches...basically anything with a color screen combine, or add, red, green, and blue-colored light in various combinations to generate about 90% of the colors you and I can see. Combining all of these primaries in equal parts will generate white light. A system like this is specifically called an RGB system (see below). Therefore, any design work meant to be viewed on a device of some kind - e.g. broadcast graphics, video, app assets, website imagery, etc - should be created in an RGB system or mode.

GDPE diagrams color systems 32Subtractive color systems arise from the filtering of light. The most common primary colors used in a system like this are cyan, magenta, and yellow. Generally, you will find this color system in the four-color printing process, where a black 'channel' or 'key' is used to register or align the other three colors together. As the alignment key, black is generally shorted to K, and the entire system labeled CMYK.

In the case of CMYK, the pigments placed upon (usually) white paper act as filters, absorbing or subtracting wavelengths of light other than those corresponding to the colors we perceive. This is why systems such as these are called subtractive: light is filtered or subtracted when colors are generated. 

Anything kind of digital work that is meant for print should be made in the CMYK space. 

 

Color Schemes

There is no right or wrong way to mix colors, as acculturation and personal preferences play a large role in what we find acceptable. However, basic color schemes that use the modern color wheel can be very useful in discovering universally acceptable color combinations. Below are the six geometrically derived color schemes, and respective examples of palettes obtained from them: 

Color schemes derived from the color wheel 

 Color Harmony

Harmony can be defined as a pleasing arrangement of parts, whether it be music, poetry, color, or even an ice cream sundae.

In visual experiences, harmony is something that is pleasing to the eye. It engages the viewer and it creates an inner sense of order, a balance in the visual experience. When something is not harmonious, it's either boring or chaotic. At one extreme is a visual experience that is so bland that the viewer is not engaged. The human brain will reject under-stimulating information. At the other extreme is a visual experience that is so overdone, so chaotic that the viewer can't stand to look at it. The human brain rejects what it can not organize, what it can not understand. The visual task requires that we present a logical structure. Color harmony delivers visual interest and a sense of order.

In summary, extreme unity leads to under-stimulation, extreme complexity leads to over-stimulation. Harmony is a dynamic equilibrium.

Some Formulas for Color Harmony

There are many theories for harmony. The following illustrations and descriptions present some basic formulas.


1. A color scheme based on analogous colors

ctheory leaf 

Analogous colors are any three colors that are side by side on a 12 part color wheel, such as yellow-green, yellow, and yellow-orange. Usually one of the three colors predominates.
 

2. A color scheme based on complementary colors

ctheory orchid  

Complementary colors are any two colors that are directly opposite each other, such as red and green and red-purple, and yellow-green. In the illustration above, there are several variations of yellow-green in the leaves and several variations of red-purple in the orchid. These opposing colors create maximum contrast and maximum stability.
 

3. A color scheme based on nature

cteory nature

Nature provides a perfect departure point for color harmony. In the illustration above, red yellow, and green create a harmonious design, regardless of whether this combination fits into a technical formula for color harmony.

Color Scheme Generators

  • Coolors.com is a very simple and straightforward color scheme generator, and it has a pretty slamming iOS app as well! I use this all the time.
  • Paletton.com provides a really excellent color scheme generator. Let's check it out!
  • DeGraeve.com allows you to create a theme from an existing image. Very cool.
  • And finally, the generator Adobe would have you use, https://color.adobe.com

Color Relativity

How color behaves in relation to other colors and shapes is a complex area of color theory. Compare the contrast effects of different color backgrounds for the same lavender square. A washed-out lavender appears more brilliant against a black background and somewhat duller against the white background. In contrast with orange, the lavender appears grayish; in contrast with blue-green, it exhibits brilliance. Notice that the lavender square appears a little larger on black than on the other background colors.

Different readings of the same color
I know this is bizarre, but that's the same dull lavender (#988ea6) across the four different backgrounds.
In the image below, the same lavender color is used as one background for a sort of dull blue. The same dull blue appears on a more saturated cyan background as well. The result appears to be two different foreground colors, but I assure you, they are the same dull blue on either side. 
Though the exact same color, the less saturated blue squares look different depending on their background. 

Observing the effects colors have on each other is the starting point for understanding the relativity of color. The relationship of values, saturation, and the warmth or coolness of respective hues can cause noticeable differences in our perception of color.

One of the first Western artists to formally experiment with color as it is perceived was Eugene Delacroix, who was much more concerned with the actual wavelengths hitting the retinas than the colors are rational brains told us we were looking at. The 2-minute video discusses Delacroix's then-unique approach to color, and how it led directly to the earliest developments of the Modern Art movement:

Stemming directly from the work of artists like Delacroix, the Impressionists raised the exploration of light and color to an entirely new level. A pejorative term at the time, the early Impressionist artists initially called themselves the Anonymous Society of Painters, Sculptors, Engravers. They were later labeled Impressionists due to the inclusion of Claude Monet's seminal landscape entitled Impression, Sunrise

Claude Monet, "Impression, Sunrise" (1872)

In the painting above, Monet was attempting to record colors and their interactions the way he perceived them, as opposed to rendering the actual colors found in each constituent piece. The result is a hazy grayish blue, resulting from the interaction of two complementary colors: orange and blue. Another result: the sun appears to glow right off the canvas due to its interaction with the surrounding blue. Monet has employed painterly techniques known at least since Delacroix, but rather than try to simply record the event, as any photograph would do, Monetpoetically used color and form to highlight his perception and memory of the event. 

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GDPE diagrams texture 12

We all implicitly know what texture is. For example, some people like pulp in their orange juice, some like no pulp; some prefer a high thread count for their pillow cases for a smooth, satiny feeling, while others like a courser fabric; some people prefer smooth peanut butter, while those of us who aren't deranged and like to keep it 9ab0c50042c1d1cab13bccd826479189 prefer chunky. 

Most of us can certainly feel texture on our body parts, but we have also learned to associate these feelings with our visual recognition of different textures. Therefore, we can see a tree trunk's texture and know ahead of time whether the bark is smooth or rough. We can see a sweater's texture and know that it will probably be soft. This is learned with experience, of course, but it means that texture is a visual element as well as physical property.
In art and design, texture is almost entirely virtual and/or invented, as opposed to real. A painting of a tree can simulate the texture of that tree with variations in light and dark (i.e. value). A 3D animation can simulate the texture skin of a dinosaur's skin, a simulation that is likewise invented, as we've never really seen actual dinosaur skin (I hope). The examples above are all images of real textures, and are thus virtual or simulated.

Texture as an element can add the properties of dimension, age, slickness, cost, speed, or even an element of danger to a form. Below is a gallery of different implied textures that illicit very different feelings.