Types of bacon
Let's get some bacon terminology sorted first. Here in Scotland and across the UK bacon comes in three forms - streaky, back and middle.
Streaky bacon is made from the belly of the pig and as such has a higher proportion of fat than back bacon. It makes the perfect crispy bacon but is probably less popular for bacon butties (sandwiches) and rolls. If you just ask for "bacon" in the USA you're highly likely to get streaky bacon.
A whole belly from a side of a pig is too large for most of us to make into bacon in one piece. We have our butcher cut ours into pieces about 30cm square, which make them easy to handle and a good size for curing.
Back bacon is made from the loin of the pig. It's got a good bit more meat on it, is leaner than streaky, and is perfect for bacon rolls and butties. In the USA this may be described as "Canadian bacon", but that term covers a multitude of sins of pork product, so be more precise if you're looking for back bacon across the pond.
As with the belly, a whole loin from a side of a mature pig is too large to handle comfortably, so cut it to a reasonable size.
Middle bacon is basically streaky and back together in a single cut. It's becoming difficult to come by in supermarkets in the UK, and less common in butchers too.
One thing all bacon has in common is that it is cured. Let's move on to talk about what that means.
Le Charcutier Anglais: Tales & Recipes of a Gamekeeper Turned Charcutier Berry Marc-Frederic
The Sausage Book Paul Peacock
Maynard: Secrets of a Bacon Curer Maynard Davies