Birds have feathers and under these hard feathers there is another layer called down. This layer provides warmth to the birds and this is the layer used by humans to fill the jackets, duvets, sleeping bags and pillows. Very young birds are only covered in down. It is really soft, light and very efficient in capturing heat due to it's loose structure. The only enemy of down is water and oil, it looses most of it's insulating abilities when wet.
How do humans get down, there is a lot of debate regarding this question. Some companies say they use ethical down. This means that when a bird makes a nest to lay eggs it plucks (using it's beak) the very down under it's feather to line the nest. This makes the nest warm and soft and ready for the chick to hatch. Another purpose served by this painful activity is that the mommy bird makes a patch of skin naked to provide warmth to the egg. After the chic starts running here and there and does not sleep in the nest anymore, the ethical down collectors then collect this handful of down and clean it. As is clear from the process there is very little down collected in this manner but the market demand is really huge for this material. What some others do is, they force feed these chicks and pluck the down off them to be sold in the market. The Chinese go a step further, they kill the bird, use the down and feather to fill sleeping bags and eat the bird.
There are three types of down available in India. Chicken feather is the cheapest source, filled in jackets and sleeping bags which are cheap replica of famous brands and sold blatantly in the open market. You can know this variety by pressing the fabric between your fingers, you will feel the hard feather bone. This bone is usually sharp at ends and comes out of the fabric by puncturing it. Products ranging between 900 to 3000 Rs. are filled with this material courtesy your local butcher. Then there is the duck down which is found in products coming out of China. There are enough videos available on the net showing how this is achieved. Many famous European and American manufacturers sourcing their products from China are selling this stuff due to cost effectiveness. Products of this variety range between 3000 to 12000. Then there are Goose down products originating from Europe. These are the top quality products used by mountaineering expeditions and sold by really famous brands. These cost a bomb and few Indians own it. Products start at 12000 and go upto 1 lakh. We Indians are known for Jugaad, we created another market for our needs. Indian Army which do not have lack of funds, buys the Goose down products for its officers and jawans. After the life of the product, they auction the products to the highest bidder. These enterprising businesses discard the shell, clean the feather and down, refill it in products and voila you have goose down at affordable prices. If you are well connected and lucky you may also get your hands on a second hand product coming from Siachin or Everest.
Feather and Down (Ratio indicator): (100% Down), (90% Down 10% Feather), as the name suggest, these figures signify the percentage of down used in combination with feathers to make it more affordable. Higher percentage of down means better quality and more money.
Fill Power: 500 / 600 / 700 / 800 fill power, higher fill power means better performance with 800 being the best in the world. Down is a cluster of fibers, higher fill power means longer length of the fiber and comes from an older bird.
Please be advised that Down / feather needs special care and maintenance. If you ever buy one after paying through your nose, we are sure you will learn to care for it too. Oily hair, moisture, washing machine all these can destroy your down product.