A duvet cover is, as the name implies, an accessory to the successful deployment of a duvet.
The cover itself is usually made of fabric and is often of proportions at least slightly larger than the duvet that it is intended for. Theoretically it is possible to deploy a duvet cover over a quilt, continental quilt, doona, comforter or almost any other bulky bedcovering such as a blanket, it has yet to be universally decided whether an object other than a duvet, becomes a duvet when encased in a duvet cover.
It is possible to deploy a duvet cover on its own, without an internal filling, in such cases the effect closely resembles the effect of two sheets.
Duvet covers invariably consist of two faces of cloth fixed at three edges to create a form of envelope, into which the duvet is placed through the fourth `open' side. This open side usually has an incorporated method for closing the envelope, mechanical fixings such as buttons, poppers and zips are common in the UK whereas throughout mainland Europe it is common to provide for the opening to be closed by supplying a copious amount of additional fabric that can be folded into the duvet, or tucked under the mattress, this is a very good idea as it prevents duvet wander.
Some duvet covers contain a mysterious feature that takes the form of small holes, or gaps in the seams at the corners, these are believed to be for ritual purposes.
Duvet covers are in a sense an admission of the fact that people make things dirty, due to the primary utilitarian function of a duvet cover being to allow the thing to be washed separately from the duvet (by implication also suggesting that the owner or user cannot be bothered to wash the whole thing).
The primary aesthetic function of a duvet cover is to give a visitor to the bed in question an insight into the taste and perhaps even the psychological condition of the bed's occupant (or in some cases the housekeeper, matron, warder etc). The insight gained is often subliminal, ranging from "mmm I always liked paisley" to "I would look fabulous draped with that retro 70's style in first light of morning". It has been suggested that 80% of one night stands are just that, due to a mismatch of duvet cover aesthetic that is only discovered in the cold light of day. In extreme cases the revelation caused by a glimpse of an intendeds duvet cover can act as an early warning to potential disaster,, signs to watch for include; duvet covers made of curious fabrics (black satin, latex, lego, brillo), duvet covers with tell-tale marks (blood, bite marks, chainsaw gashes, scales), or unusual fillings.
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