The process of curing meat (including fish, shellfish, and poultry) is an ancient process, the origins of it lost in antiquity. The origin of our verb to cure comes from the Latin verb curare, meaning “to take care of”. The word passed into Middle French as curer, and after the Norman conquest in 1066 into what became Middle English as curen. Thus is shares its roots and ultimate meaning as the medical use, “to take care of”.
Real curing requires salt, but for several reasons salt alone is not the ideal curing agent. In a truly cured meat (I shall continue to use that term to include the items in the first sentence), the salt content is high and the moisture level is low. Remember, the primary purpose of curing is to prevent bacterial and fungal attack on the meat, but there are other factors at play as well.