Contrast

The difference in quality between two instances of an art element, or using opposing qualities next to each other. For example, black and white (contrasting values), organic/curvy and geometric/angular (contrasting lines/shapes/forms), and rough and smooth (contrasting textures).

The greater the contrast, the more something will stand out and call attention to itself. This applies to whole works of art as well as areas within an artwork. Areas with greater contrast in value (stronger darks and lights) will tend to appear more forward in space, as over distance atmospheric haze lessens contrast (atmospheric perspective). Contrast can also be used to set the mood or tone of the work. High contrast makes a work more vibrant, vigorous, brash, lively - it "pops" more. Low-contrast work is more quiet, calm, subtle, reflective, soothing.