Only Down is birds' fine, soft insulating feathers. Down that people use comes from ducks and geese. Eider down, the softest and warmest, often promoted as ideal, is the down of the Eider duck.
Eider ducks use their down to line their nests and cover their eggs.
Workers in Eastern European countries, the source of most commercially available down, rip the feathers by hand from the necks and breasts of live, fully-conscious geese and ducks after tying their feet together and hanging them upside down. Afterwards, traumatized and in agony, the birds tremble uncontrollably and huddle together or find a structure to lean on for support in their shock. It takes them several days to recover. Workers allow the birds' feathers to grow back and subject them to the same ordeal four or five times in their lives. Now that we know to take animals' well-being into account, we know that down is only good when left on the birds.