Labeling objects by color is a simple yet effective way to categorize things. Imagine a world where all objects have been assigned a specific color, and you can instantly identify what something is by its hue.
Labeling objects by their shape can be useful in situations where color isn't enough. Imagine a world where all objects have been assigned a specific shape, and you can instantly tell what something is by its form.
Labeling objects by their size can be useful in situations where shape and color aren't enough. Imagine a world where all objects have been assigned a specific size, and you can instantly tell what something is by its magnitude.