What is texture? Well, it is perhaps best defined as surface detail. Objects become much more interesting when their surfaces are seen in exquisite detail rather than as bland or smooth areas of colour.
Texture is always present in an image and can be used very successfully to enhance the illusion of depth. Look for good light striking the textured object at an optimum angle. For example, wonderful texture may be found in the faces of elderly people. Add low light and the texture can turn a mediocre portrait in to a stunning image.
A number of different approaches can be adopted when using texture in an image. Texture can become the subject of an image in its own right., but to do this successfully a photographer needs an appropriate subject featuring good colour and tonal contrast. It is also usually important to get close to the subject so the texture can be seen in some detail, and use side lighting to enhance contrast.
In many images the texture of objects is used merely to add supporting interest to an image. In a landscape the centre of interest may be far away from the foreground detail. However the rocks, or whatever forms the foreground, can be made much more interesting by capturing their texture. This supporting role for texture is widely used.
Finally, texture can be used to convey information about the principal subject of an image. By revealing the texture of an elderly person's face we emphasize the age and experience of the subject. Equally, by capturing the smooth and unblemished complexion of a young girl, we emphasize her youth and fragility.