Because photographs only exist in two dimensions (height and width) and have no depth (the third dimension), it's important to emphasize textures to give photos a "touch" factor. There are all kinds of textures that can be brought out in a photo, from the slippery smooth surface of wet seaweed to the rough surface of a gravel parking lot. Bringing out the texture is largely a matter of getting close enough to it so that it shows clearly and then using lighting to exaggerate it. Light that comes from the side or the rear of your subject works best because that kind of oblique lighting creates lots of tiny shadows and highlights and it's that contrast that draws out the surface quality of subjects. Sometimes top lighting will also draw out textures, as long as the angle is steep enough. For example, I shot this old peeling carving of a Chinaman with the light coming from almost directly overhead and the lighting created a lot of shadows running down on the face--under the eyebrows, nose, lips, etc. And by filling the frame with just the face, the eye is drawn naturally to the textures. If you're bored someday while shooting, forget about subjects and go look for a texture--you might find that the texture alone is a good enough subject.