Despite what many believe, “tonnage” is not a measurement of weight. Rather, it is the volume of the cargo or the ship's internal volume. Tonnage is a determining factor in several aspects such as port costs, vessel abilities, and adherence to regulations. Gross tonnage refers to the total internal capacity of a ship, including all its enclosed spaces. In contrast, net tonnage disregards spaces that do not generate revenue, like crew quarters and machine compartments.  The concept of tonnage carries historical importance, stemming from the era when ships were levied based on their cargo capacity. Currently, tonnage is instrumental in deciding a ship's aptitude for different shipping operations. For instance, bulk carriers are made to haul large volumes of loose cargo such as coal or grain.