Formal Aspects

All objects have surfaces. And all surfaces have textures. Texture is the appearance and feel of the surface and also refers to the variations on the surface. Texture is defined by the quality of the surface’s structure or pattern.

Textures may be plain or decorated, smooth or rough, shiny or dull, transparent or opaque, matte or glossy, and, soft or hard.

Texture is created by massing together small visual elements or particles into an arrangement whose visual character derives from their combination as a whole. The character of the texture varies in terms of the structure of the individual elements and the spaces in between them.

Textures in the physical world:
Materials in the physical world have different textures. These are tactile and can be physically felt by the sense of touch. Textures that can be felt are referred to as 'tactile'.

Textures in the represented world: 
Textures when represented on an image or illustration are perceived as the actual texture of the surface. Here the surface quality is felt through the sense of sight. 
These textures are referred to as 'visual textures'.

Semantic Aspects

Textures show the quality of the physical surfaces. It can express meanings and can be designed to be rough, smooth, earthy, old, futuristic, fresh, energetic, and so on.

Textures can also be abstract, symbolic or descriptive.

Practical Aspects

Textures depict the characteristics of the surface. It can be designed to be soft, smooth, rough, rugged, shiny, sticky, etc. depending on the function it is supposed to serve.

Texture gradients are a useful means for the depiction of depth.