After you cut down a white oak tree, you have a choice for how you turn that tree into lumber. How you decide to cut it, and what part of the tree it comes from, determines whether each board is considered flat sawn (aka plain sawn), rift sawn or quarter sawn. This article from Fine Homebuilding has a great visual showing the differences. When it comes to white oak, the primary differences are aesthetics and stability, and along with that, price. When it comes to aesthetics, rift and quarter sawn oak will often show the much sought after "rays", that almost look like tiger stripes in the wood. (See the images here.) Flat sawn is not without its appeal, however, as it can often produce beautiful arches caused by the exposed rings. The other aspect is stability. Rift and quarter sawn oak will expand and contract less along the width of the board than flat sawn will, by a factor of about 1.7. The reduced wood movement means certain joints are less likely to be under stress.