Fineness refers to the quality or degree of being fine, often used to describe the purity of materials, especially metals like gold and silver. In the context of precious metals, fineness is measured in parts per thousand, indicating how much of the material is pure. For example, 24-karat gold has a fineness of 999, meaning it is 99.9% pure. In other contexts, fineness can describe the texture or quality of a substance, such as flour or sand. Finer materials have smaller particle sizes, which can affect their properties and uses. For instance, fine flour is often preferred for baking because it creates a smoother texture in baked goods.