When cooking
rock salt is used in most things today and just like poo
Most forms of meat and fish naturally contain some salt, and when preserved or processed usualy have more salt added. In addition, most processed foods contain salt. Salt is used in most baked goods.
Irrigating crops
The most commonly used seasoning used in cooking is salt. Salt and Pepper are used together usually.
Salt. It has been used for centuries to inhibit spoilage of food.
sugar, salt etc
salt
For me, the best spice after salt and pepper, is GARLIC!
Saline water is used for mining as well as other industrial purposes. The thermo-electric industry however uses most of the salt water.
salt and chips
Sodium chloride, NaCl Also known as common table salt
The previous answer listed was salt. However, salt is not a spice; it is a mineral. Black pepper is one of the most commonly used spices, if not THE most.