Down comforters are one of the more popular ways of staying warm when the chill of winter fills the air. Made from duck or goose down, they are available in a wide range of prices, depending on the type of down and the surrounding material, among other things.

There are a few things you should know when shopping for a down comforter. For example, a down comforter has a fill power rating. This number corresponds to the comforters fluffiness -- the higher, the better. Over 800 is considered the most luxurious -- and most expensive -- but anything over 550 is good.

Thread count is another important consideration when shopping for a down comforter. Thread count measures the number of threads per square inch. Again, higher numbers are better as this makes a lighter, softer comforter.

Down comforters can be made from a number of materials. They can be made from either duck or goose down. Duck down is much less expensive, largely due to its odor. Some of the less expensive comforters also include feathers. Feathers are added to add bulk and firmness, but they are sharp and can prick your skin. Generally, the higher the amount of down, the higher the price will be. The best down comforters are those made from Siberian Geese. These comforters are the heaviest and have the best longevity.

Some people are allergic to down comforters. More specifically, they are allergic to the dust mites and particles that reside in down comforters. For those folks, there are hypoallergenic down comforters, such as Hyperclean and TempraKON. Hypodown is a hypoallergenic mix of goose down and milkweed. Organic lamb wool, alpaca wool, and llama wool are also good alternatives for allergy sufferers.