A salt road refers to any of the prehistoric and historical trade routes by which essential salt was transported to regions that lacked it.
Sign for historic salt road in Bavaria
A camel train for salt transportation in Afar Region of Ethiopia
In common usage, salt is a mineral composed primarily of sodium chloride (NaCl). When used in food, especially in granulated form, it is more formally called table salt. In the form of a natural crystalline mineral, salt is also known as rock salt or halite. Salt is essential for life in general, and saltiness is one of the basic human tastes. Salt is one of the oldest and most ubiquitous food seasonings, and is known to uniformly improve the taste perception of food, including otherwise unpalatable food. Salting, brining, and pickling are also ancient and important methods of food preservation.
Rock salt (halite)
Salt production in Halle, Saxony-Anhalt (1670)
Ponds near Maras, Peru, fed from a mineral spring and used for salt production since pre-Inca times
SEM image of a grain of table salt