The physical properties of matter are quantifiable and observable traits of the material that can be measured, without changing the composition of the matter. Appearance, texture, color and odor are examples of matter physical properties.
Physical properties are used to identify and describe matter. Commonly used physical properties in science include melting and boiling points, density, solubility and polarity. Transformations in matter are often accompanied by changes in physical properties, such as the increase in density that accompanies the transition of water from a liquid to a gas.
Physical properties are often classified into intensive and extensive, based on whether they rely on the amount or geometry of matter in the object. Properties that change when the amount of material is changed are extensive, while those that are independent of the amount of material are intensive. An example of related intensive and extensive properties is electrical resistance versus electrical resistivity. The former is an extensive property, because it increases with the increase in material length and decreases with the increase in material cross-sectional area. The latter is independent of material geometry, and it can be specified as the resistance of a unit length and width of material.
Physical properties can be defined based on the direction of their occurrence. If all directions in the material yield the same physical property, the property is said to be isotropic. If the property is dependent on direction, it is called anisotropic.