Curing salmon is a way of seasoning and preserving salmon that has been around for centuries. Before refrigerators and freezer, curing was a way to keep meat for longer. Smoking salmon can have the same outcome, but it introduces different flavors and is a different process. Smoking does use salt and other seasonings as part of a brine, but the preservation mostly comes from the smoking process. In a cure, salt is the main preservative. Moisture is one of the necessary factors needed for bacteria to grow, and both curing and smoking reduce the amount of moisture in the salmon.