This first myth, that salt and sodium are the same, is just that: a myth. Sodium is an essential part of salt, which is also known as sodium chloride, but sodium is also found in many other places. Sodium is an alkali metal, like potassium, and is not only used to flavor our foods, but also as a preservative, binder and stabilizer.
It's important to read food labels, including both the nutritional facts -- where the amount of sodium in the product is listed -- and the ingredients list. Salt is an obvious source of sodium, but also look for other forms, including any word or phrase that begins with 'sodium,' such as sodium citrate, sodium bicarbonate (baking soda), sodium benzoate, sodium chloride, sodium saccharin and sodium stearoyl lactylate among others. Also keep an eye open for sodium sources that may not be as obvious, such as disodium phosphate, monosodium glutamate (MSG) and trisodium phosphate.