The Edible Chicken
Chicken is a type of poultry, that is, a bird raised for the dining table, not a wild or game bird. The domestic chicken, Gallus domesticus or Gallus gallus, is thought to be descended from the Southeast Asian red jungle fowl, Gallus bankiva (gallus means comb in Latin). Though originally domesticated for fighting, today chickens are bred for meat, eggs, and feathers. It's the meat I'm going to focus on here.
Chicken is versatile: it can be served whole, cut into pieces, or ground; and can be baked, fried, roasted, grilled, broiled, boiled, stewed, steamed, smoked, or barbecued. As far as I know, no religion that allows the eating of animal flesh forbids the eating of chicken meat, so chicken is suitable for a wide range of palates. Many people who won't eat beef or pork will consume chicken. Chicken also has the advantage in the western world at least of being relatively inexpensive, though this was not always the case. It only became cheap after World War II when mass chicken production emerged. More on that in a minute.
Chickens range in size from 1 lb (about .5 kg) to 10 lbs (about 5 kg). The smallest are rock cornish hens and squab chickens, squab broilers, or poussins (not to be confused with squab, a game bird). The diminutive rock cornish hens, a cross between white Plymouth rock and cornish chickens, are slaughtered (let's not mince words here, that's what it is) when 4-6 weeks old; they are usually just over a pound in weight (about 2.5 kg), and as such are of a perfect size for a single serving; they are usually roasted whole - sometimes stuffed - or split along the backbone, butterflied (laid flat) and broiled. Poussins are regular chickens that are also killed when very young; harder to come by, they are usually prepared in a similar way to cornish hens.
Larger whole chickens come in a range of grades. They may be labelled "broiler-fryer" or "roaster" chickens; chicken parts (breasts, wings, drumsticks etc.) will generally be cut from one of these two types of bird. The former are a few months old, the latter up to 8 months old. Roasters have a higher fat content and so are indeed most suitable for roasting. "Stewing chickens" are a year or more in age; this greater age makes them more flavourful but also tougher, so they are best cooked with moist heat. A capon is a rooster that's been castrated, fattened up, and killed at about 10 months; it's very tender and juicy and suited for roasting.
I should also mention kosher and halal chickens. Halal chickens are hand-slaughtered by someone of the Muslim faith, unlike most chickens, which are machine-slaughtered by stunning or suffocation. Kosher chickens are processed according Jewish dietary laws, which involves ritual slaughtering under the supervision of a rabbi, after which the chickens are defeathered, soaked, brined, and dried. Cook's Illustrated, the cooking magazine for the fuss budget, recommends brining chicken for moistness and flavour; if this is too much work, buy kosher chickens instead.
There's some grisly terminology in there, and rightly so, for the raising of chickens on farms is rather disgusting. Chickens are big business, and they are raised in tiny 1 foot square cages stacked one atop the other in huge stinky sheds; the chickens crouch in these tiny wire enclosures with nothing to do but eat, shit, and sleep. In these cramped quarters they have little possibility of movement and have no view of green or sunshine. It's a totally artificial environment. If you've ever been in a chicken farm - more properly factory - you won't forget the noise, the smell, the crowding. In such conditions disease can spread quickly, and so factory-raised chickens are fed huge amounts of antibiotics to control illness and hormones to fatten them up faster for market.
Now, I've raised chickens that roamed free, and they're not too bright; it's hard for me to have much respect for a chicken. But I've also been in a chicken factory, and I care about what I eat. So I go for the free range chicken, or even organic chicken, when I can. A free range chicken has a 2 foot square cage as well as access to out-of-doors, though the outdoor pen itself may not be large. Organic chickens are almost always also free range chickens; they are raised without antibiotics on feed that comes from organic fields. No doubt they're still killed in horrifying ways, though.
Chicken should be stored in the coldest part of the refrigerator, generally at the back near the top, and eaten within a day or two. If you can't consume it that fast, freeze it; it will be fine for up to a year, but it'll have the best texture if you eat it within a month or so. Thaw chicken in the fridge or in cold water before cooking.
The thing to really be cautious of with chicken and all poultry is not to allow surfaces that have come in contact with raw chicken - knife, cutting board, hands - touch cooked chicken (or turkey). So always wash these objects thoroughly while the chicken is cooking to avoid salmonella.
I should add that raw chicken is used to make sushi in Japan. Apparently the chickens are raised and prepared in very hygenic conditions, but a life of warnings about the dangers of un(der)cooked chicken made me recoil after I had taken one bite the one time I was served this delicacy.