Poaching means to cook something in simmering (where little bubbles form, before it's actually boiling) or almost simmering liquid, about 160-185°. If you bring it to a full boil, it will break down the food instead of gently cooking it. Boiling tends to make meat tough. With poaching, the meat will stay moist and tender, and this cooking method requires no fat. Here is a technique that you will want to remember for those days when time is really tight, everyone is hungry, and can’t wait to eat. This is the best method for chicken salad. The meat has a texture you cannot obtain with any other cooking method. It is almost silky smooth.
You can also choose from a huge array of liquids in which to poach; the most common are simple water, wines of varying sorts, and stocks (concentrated broth). In addition to the liquid you choose, you can greatly affect the flavor of what you cook like this by adding 'extras'; onion, garlic, spices of all sorts, vegetables, and so on.
Put your chicken pieces, bone in or boneless, skinned or skinless, in a pan big enough to cover them with water. Cover with water and bring to a boil. Turn heat to low and simmer for 15 minutes. Remove from heat and let stand for 15 minutes. Drain the water and use it for soup. Cover with cold water for 10 minutes until cool enough to handle. The skin and bones pull off easily. They can be saved for soup, too. Shred or dice the meat as your recipe directs.