What is Volume?
:''This article is about physical object; for meaning from audio field, see [[loudness]].'' {{wiktionary}} The '''volume''' of an object is a measure of the amount of [[Space (physics)|space]] occupied by that object, and is not to be confused with [[mass]]. The volume of a mountain is much larger than the volume of a rock, for instance. By convention, the word volume implies a [[3-D|three-dimensional]] context where: * The [[length]] is the longest distance between the object's extremities. * The [[width]] (or breadth) refers to the size of the object in a direction perpendicular to its length. * The [[height]] (or [[depth]]) stands for the size of that object in the direction perpendicular to both the length and the width. For objects at or near the [[Earth]]'s surface, height or depth often refers to the dimension of the object along the local vertical. All physical objects occupy a volume, even if some are so thin that they appear to be [[2D|two-dimensional]], like a sheet of paper. == Units of volume == The unit of volume in the [[International System of Units]] is the cubic meter, which is represented by the symbol m<sup>3</sup>. In some fields or applications, one often uses different units to simplify the discussions or writings. For instance: * Everyday quantities of [[liquid]]s are often measured in units of a [[litre]], written as L, which is the volume occupied by a cubic decimetre. * Large quantities of liquids, such as [[oil]], and sometimes other materials, may be measured and traded in units of [[barrel]]s. There are many different reference volumes called barrels, depending on the nature of the content. Traditional units are still in encountered in some countries: [[Imperial unit]]s such as the [[gallon]] or the [[fluid ounce]] were in widespread use within the [[British Empire]]. Some of them are still popular in the [[United States]], which also uses units like the [[bushel]], the [[quart]], the cup and the teaspoon (in cooking recipes, for example). See [[U.S. customary units]] for mor