Anisotropy refers to the directional dependence of a material's properties. This means that a substance may exhibit different characteristics, such as strength, conductivity, or refractive index, when measured along different directions. For example, in materials like wood or certain crystals, the arrangement of fibers or atoms can lead to variations in how they respond to stress or light. In contrast, isotropy describes materials that have uniform properties in all directions. Understanding anisotropy is crucial in fields like materials science, geology, and physics, as it influences how materials behave under various conditions and can affect their applications in technology and engineering.