Almost every preparation benefits from using a flavorful cooking liquid instead of water. You get a heartier beef stew using beef broth -- a more floral vegetable soup using vegetable stock -- and a fuller flavor from chicken dishes made with chicken broth. It takes about 30 minutes to simmer a chicken breast and 1 to 1 1/2 hours to simmer a whole chicken -- check the minimum internal temperature for doneness, 165 degrees Fahrenheit, using a digital thermometer to make sure. Don't rinse chicken before you boil it -- boiling alone kills bacteria and purges impurities.
Boiling vs. Simmering
Different recipes sometimes call for different variations of boiling, even when talking about the same dish -- rolling boil, boil, and simmer are often used interchangeably. But you only need care about two types when cooking chicken: rolling boil, where the broth bubbles vigorously -- as when cooking pasta -- and simmering, or when the broth barely bubbles. Simmering allows you to judge the level of broth during cooking and skim the surface as needed, and it uses less energy -- overall it's a more efficient technique than boiling. But you need to bring the broth to a rolling boil after you add the chicken so it so it starts purging impurities as soon as possible. So as a general rule, boil first, simmer later.
Stock or Broth
You can use chicken stock or chicken broth interchangeably in almost all instances. The only difference between the two is seasoning -- broths typically have salt whereas stocks do not. If you have unseasoned stock instead of broth, simply season it to taste with salt before you add the chicken. If you're using broth, don't add salt -- it's that simple. But if you have a choice between stock or broth, always go with stock. Unseasoned cooking liquids give you more control over the saltiness of the dish.
You find several sodium-free stocks in the supermarket, but you can make it at home: Simmer a few pounds of chicken bones and mirepoix -- a mix of chopped onions, carrots and celery -- in enough water to cover for a couple of hours, and strain.
Skin-On or Skinless
Don't go out of your way to use skin-on chicken breasts when boiling. The minimal skin on the breast only adds flavor when it's fried, and unless you enjoy its rubbery consistency, you're better off buying skinless -- unless skin-on breasts are on sale, in which case buy those and save the skin for another use. If you're instead boiling a whole chicken for soup, leave the skin on and discard it after cooking -- it's adds a lot of flavor to the already flavorful broth.
Basic Boiled Chicken
Add the whole chicken or chicken breasts to a pot and cover with cold chicken broth or stock. Add a few handfuls of vegetables -- maybe 1/2 cup per breast or 4 cups per whole chicken -- and bring the broth to a rolling boil. Boil the chicken for 3 or 4 minutes, using a spoon to scoop off the foam and impurities that collect on the sides of the pan. Next, lower the temperature until the broth barely bubbles, and cook until the breasts and, if applicable, the thighs, reach 165 F.
After you boil chicken breasts, slice them and serve, or let them cool for a minute and shred them for salads, sandwiches or dumplings -- whatever you fancy. To make chicken soup, remove the chicken from the broth. Strain the broth through a strainer into a pot. Cook noodles and vegetables in the broth, add shredded chicken and season it to taste.