© Denzil Green
Bacon is made from cuts of meat from the side, back or belly of a pig. The meat is cured, and sometimes smoked after that. It is almost always sold raw, though now some pre-cooked, highly-packaged options are available.
In North America, pieces of bacon are referred to as slices; in the UK, they are referred to as "rashers." A whole side of unsliced bacon is called a "flitch."
British Bacon, Irish Bacon, and the style of bacon that Americans call "Canadian Bacon" is quite lean, coming from the loin of the pig. North Americans tend to use the phrase "Back Bacon" to describe any type of Bacon like this which isn't streaked with fat.
American-style bacon has as much or more fat than meat in it. It comes from the belly or side of the pig, so it will be 50 to 70% fat (close to what is called in Britain "streaky bacon", though even their "streaky bacon" will generally have more meat in it.)
American bacon is generally cooked until it is crisp, as it is mostly fat. You wouldn't do that with British or Canadian bacon, as it is mostly meat -- it would just dry out. American bacon will generally produce enough of its own fat for frying in; the other types of Bacon, because they have so little fat, are best fried in a little butter or oil to prevent their sticking.
Streaky bacon is not normally used for sandwiches or for breakfast in the UK -- Back Bacon is more usual for that. Instead, in the UK Streaky is more generally used for "larding" other meat with, or cooking with in a dish such as a pasta, a pâté or a terrine.
Sometimes when you cook bacon, it leaks coagulated, milky secretions. This is salt and water; it comes out of bacon that has been cured with brine ("wet-cured"), either by injecting the brine into the Bacon, or soaking the bacon in brine (almost always by injection these days.) Phosphates are often added to the brine to help the meat retain the water better. The brine both gives the bacon a cured taste in a few hours (as opposed to several days for dry cures), and increases the weight of the bacon and therefore the manufacturer's profits. From the consumer point of view, the issue isn't just paying meat prices for water; it's also that owing to the added water, the bacon doesn't cook properly. It ends up steaming in the pan and exuding a white gunk, instead of browning and turning crisp and golden.
Bear in mind that even before the brine injection, pork naturally already contains about 30% water. That percentage is counted as the percentage of the bacon product that is meat, because it's naturally present in the meat. Traditional dry curing evaporates much of that natural water out: injection curing adds to that water content. Typically, super-market bacon contains up to 10% added water, and will be about 87% pork (including the 30% water already present.) Dry-cure bacon, though more expensive, is about 97% pork with no added water (the remaining 3% being salt, sugar, preservatives, etc.)
In 2011, new European Union regulations were passed about bacon injected with water. Under the new rules, bacon that contains more than 5% water in it must be labelled "bacon with added water" and state the percentage of water. Retailers objected, warning that the new regulation would confuse people, and force the price of bacon up, but consumer associations said, "Most consumers would be shocked at how much water’s added. It is tempting for the food industry to do it because it is free and because they sell meat by weight. It is important that consumers know how much water is added so they can judge value for money." 
The greatest proportion of "Canadian Bacon" in the world is, in fact, made and consumed in the America now. Much of British bacon now actually comes from Denmark. There are far more varieties of bacon in the UK than there are in North America.
Sometimes you can buy bacon with the skin -- or "rind" -- still on, though most times it is sold rindless.
Sweet Cure bacon has sugar either rubbed into it while dry-curing, or sugar added to the brine while wet-curing. Maple Cure bacon is the same, but with maple syrup instead of sugar.
Bacon remains king of the breakfast meats. Aside from breakfast, though, we don't reach for Bacon near enough to add great flavour and fat to other dishes and meats. Adding bacon to other dishes can be a good way to still enjoy its taste while using it in moderate quantities in order to reduce fat and sodium intake, etc.
Around 2010 or so, a craze for bacon started to sweep the United States and Britain, leading to bacon-themed food such as bacon brownies, bacon flavoured toothpaste, bacon flavoured vodka, bacon on or in ice cream, and even, bacon-themed holidays. Some speculate that the spark that set it off was Heston Bloomenthal's bacon and egg ice cream in 2004 (though a few ice cream places in America had tried bacon ice cream before.)
In Britain, as of 2011, consumers spend £1.5 billion yearly on bacon. Two-thirds of that is made from imported meat. In 2012, British bacon consumption went up 4% from 2011. 
Unsmoked Streaky Bacon
Before starting to cook any kind of bacon, whether in a frying pan, under the grill or broiler, or on a griddle, place a piece or two of paper towel on a plate (for draining when the bacon is cooked) and set aside.
The following directions apply to cooking American or Streaky bacon. Choose a frying pan that is going to give you lots of room for your bacon, and that is wide enough for the strips to lay flat in without overlapping (though of course there are times when you need to cram as many in as possible). Put the bacon in the cold frying pan, then put the frying pan on the stove and turn the heat on to medium. (Starting in a cold pan reduces shrinkage.) Within a few minutes the bacon strips will start to sizzle and shrink. Flip them with a fork. Two to three minutes after the bacon has started to sizzle, drain off some of the Bacon fat (draining some of the fat produces crisper bacon.) You can tip the pan to drain the fat into a small dish, or use a turkey baster to siphon it out with. If you are cooking on a griddle, there will likely be a drain system on it so that you won't need to do this. Let the bacon cook for another minute or two, flipping frequently until brown, then transfer to plate with paper towel, drain and serve.
If you are cooking Canadian or British bacon, heat the pan first with a little butter or oil in it before adding the Bacon, and ignore the parts about the Bacon shrinking and needing to drain the fat.
To microwave (though many say they don't like it microwaved), place a piece of paper towel on a plate, and lay the Bacon out on that without letting any pieces overlap. Cover with another piece of paper towel. Cook at high power: how long will depend on how much umph your microwave has, but generally you need to allow more time the more slices of Bacon you are cooking at once. Start trying these lengths of time, and then adjust for your microwave: 2 slices -- 1:30 minutes; 4 slices -- 3 minutes. 6 slices should take about 6 minutes. If you have more Bacon to cook, you can make layers of paper towel and Bacon -- just make the Bacon layers go criss-cross to each other.
Save Bacon fat for future cooking uses. It has more flavour than butter, and if you are going to be cooking with a saturated fat anyway, why not use one that has more flavour so you need less of it?
To discard Bacon fat, do your drains a favour: put the fat in a tin, let it solidify, then put into garbage can.
1 pound of Bacon = 450g = 3 cups crumbled, cooked Bacon
1 pound Bacon = 450g = 10-15 thick slices / 26-24 average slices / 25-30 thin slices
Bacon is easy to freeze. Freeze it as strips, though, not as an entire package, to give you more flexibility in using it. Make a small packet to freeze by taking a long piece of plastic wrap, placing a strip of Bacon at one end of it, fold that over in plastic wrap once, place another strip on, fold over in the plastic wrap, and continue until you have used up all of that strip of plastic wrap. Make more packets as needed to accommodate all the Bacon that you have. Wrap each packet in tin foil, and freeze for up to a year. Using this method, you can easily extract 3 or 4 pieces of Bacon when you need just that without having to thaw it all.
Cooked Bacon can be wrapped in plastic wrap and stored in refrigerator for up to 5 days, or frozen for a few months. To reheat (and to make American Bacon crispy again), zap in your microwave for about a minute.
Literature & Lore
"Life expectancy would grow by leaps and bounds if green vegetables smelled as good as Bacon." -- Doug Larson (English author, 1902-1981)
 Quinn, Sue. Bacon and baconalia: has it gone too far?. Manchester, England: The Guardian. 13 July 2012.
Clay, Xanthe. Why adding water to bacon reduces its phwoar factor . London: Daily Telegraph. 28 July 2011.
Ehrlich, Richard. Water in bacon: new rasher regulations. Manchester: The Guardian. 27 July 2011.
Niamh Shields. Author, Eat Like a Girl blog. "When eating bacon, you're not really thinking about anything else."
Prince, Rose. Tried and tested: bacon. London: Daily Telegraph. 1 April 2011.
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