Layering is a technique that most of us do without knowing it’s an actual paper crafting technique. Basically, it’s the construction of a project using different layers of paper or card, often with further techniques or embellishments applied to each layer. White on white cards rely on different layers and textures, rather than colour, to distinguish between the different areas.
Layering is also a technique many colourists use, but rather than layers of paper, they will lay down layers of colour. If you watch colouring or painting videos, you will notice that the artist never stops at just one application of a medium. Rather, they build up the intensity and depth of colour gradually, often mixing different tones and tints to achieve shape and dimension.