Texture: the way that a surface feels or that it looks like it feels. texture can be sensed by touch or sight. There are two types of texture.
1. Actual Texture: texture that can actually be felt. For example, feel the difference between the carpet and a table top. The carpet is soft and rough, while the table top is hard and smooth.
2. Simulated Texture: texture that is created visually. You can draw objects so they apear to be smooth, rough, hard, squishy, sticky, etc.
Which of these textures above looks the smoothest? The roughest? The sharpest? The softest? it is with texture that we lure an observer into the picture to ask, "How did they do that?" In the bottom picture, the first segment of the drawing looks pretty flat, like it doesn't have much texture at all. The second one looks like it has some texture, and the third one actually looks wet. The last one looks like you could actually touch it and feel the raised areas and the indentations. This is what simulated texture is for.
