Bacon is a cut of meat taken from the sides, belly, or back of a pig, then cured, smoked, or both. Meat from other animals, such as beef, lamb, chicken, goat, or turkey, may also be cut, cured, or otherwise prepared to resemble bacon. Bacon may be eaten fried, baked, or grilled, or used as a minor ingredient to flavour dishes. Bacon is also used for barding and larding roasts, especially game birds. The word is derived from the Old High German bacho, meaning "buttock," "ham," or "side of bacon," and cognate with the Old French bacon.

The USDA defines bacon as "the cured belly of a swine carcass"; other cuts and characteristics must be separately qualified (e.g., "smoked pork loin bacon"). If bacon is USDA certified, then it has been treated for trichinella, a parasitic roundworm which can be destroyed by heating, freezing, drying, or smoking.

In continental Europe, this part of the pig is usually not smoked like bacon is in the United States; it is used primarily in cubes (lardons) as a cooking ingredient, valued both as a source of fat and for its flavour. In Italy, this is called pancetta and is usually cooked in small cubes or served uncooked and thinly sliced as part of an antipasto. Uncooked streaky bacon

Smoked bacon

In America, bacon is usually smoked, and different flavours can be achieved by using various types of woods or turf. This process can take up to ten hours, depending on the intensity of the flavour desired. The Virginia House-Wife (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 America unsmoked streaky bacon is usually refered to as side pork.

Cuts of bacon

• Streaky bacon comes from the belly of a pig. It is very fatty with long veins of fat running parallel to the rind. This is the most common form of bacon in the United States. Pancetta is Italian streaky bacon, smoked or aqua (unsmoked), with a strong flavour. It is generally rolled up into cylinders after curing.
• Back bacon comes from the loin in the middle of the back of the pig. It is a lean meaty cut of bacon, with relatively less fat compared to other cuts and has a ham-like texture and flavour. Most bacon consumed in the United Kingdom is back bacon. Also called Irish bacon or Canadian Bacon.
• Middle bacon is much like back bacon but is cheaper and somewhat fattier, with a richer flavour.
• Cottage bacon is thinly sliced lean pork meat from a shoulder cut that is typically oval shaped and meaty. It is cured and then sliced into round pieces for baking or frying.
• Jowl bacon is cured and smoked cheeks of pork