Bacon is cured through either a process of injecting with or soaking in brine or using plain salt (dry curing).
In America, bacon is usually cured and smoked, and different flavours can be achieved by using various types of wood, or rarely corn cobs; peat is sometimes used in the United Kingdom. This process can take up to eighteen hours, depending on the intensity of the flavour desired. The Virginia Housewife (1824), thought to be one of the earliest American cookbooks, gives no indication that bacon is ever not smoked, though it gives no advice on flavouring, noting only that care should be taken lest the fire get too hot. In early American history, the preparation and smoking of bacon (like the making of sausage) seems to have been a gender-neutral process, one of the few food-preparation processes not divided by gender.
In the United Kingdom and Ireland, smoked and unsmoked varieties are equally common, unsmoked being referred to as "green bacon".
Bacon is distinguished from salt pork and ham by differences in the brine or dry packing. Bacon brine has added curing ingredients, most notably sodium nitrite, and occasionally potassium nitrate (saltpeter), but sodium ascorbate or erythorbate may also be added to accelerate curing and stabilise colour. Flavourings such as brown sugar or maple syrup are used for some bacon products. Sodium polyphosphates, such as sodium triphosphate, may also be added to make the product easier to slice and to reduce spattering when the bacon is pan-fried. Today, a brine specifically for ham includes a large amount of sugar. Historically, the terms "ham" and "bacon" referred to different cuts of meat that were brined or packed identically, often together in the same barrel.