Final answer:
Wood shrinks most perpendicular to the grain and very little parallel to the grain, due to the anisotropic nature of wood's cellular structure affecting its contraction or expansion with changes in moisture content.
Step-by-step explanation:
Wood shrinks most in the direction perpendicular to the grain and very little parallel to the grain. This occurs because wood is composed of elongated cells aligned with the grain, which means when moisture content changes, the wood contracts or expands more drastically across the grain where cells are not aligned, compared to along the grain where cells are aligned end-to-end. That's why woodworkers must take into account the anisotropic nature of wood when building furniture or structures, to avoid potential warping or cracking due to shrinkage or expansion over time.