Texture can be tactile or visual . Tactile texture can actually be felt. For example, a piece printed on uncoated, rough paper or the use of embossed type will result in a tactile texture. Visual texture creates the illusion of texture on the printed piece. Pattern is a kind of visual texture.
Patterns work well as backgrounds or borders in layouts.
Give the piece a mood or a personality. Create contrast for interest. Fool the eye. Provoke a particular emotion. Create a feeling of richness and depth.