A mummy is any body that has been preserved from decay. Mummies can be created through a complex embalming process or accidentally through naturally-occurring preservation (as when a person dies in an extremely dry area and is covered by sand.) Mummies created through complicated embalming tend to look down upon those created accidentally.
In Britain "mummy" can also mean "mommy." This is creepy.
The ancient Egyptians elevated mummification to a high art. Because the internal organs of a corpse contain bacteria that causes putrefaction, these organs were removed and the abdominal cavity filled with resin-soaked bandages. The organs were buried separately in ceremonial vessels called canopic jars. Since the brain liquefies after death, it could often be simply drained out through the nose using a special hooked implement.
The mummy would then be washed with embalming chemicals and laboriously wrapped in linen bandages. The care taken with the body would depend on the wealth of the mummy's family -- there were undoubtedly many different levels of service available at the House of Death, ranging from the Deluxe All-Inclusive Royal Burial to the Value Vat.
The Egyptians believed that a soul was divided into three parts, the ka, the ba, and the akh. The ka was a person's double, the exact physical and emotional replica of the deceased. It had limited life and needed to remain near the corpse at all times. The ka needed offerings of food and water to survive, which is why mummies were always buried with these. The ba was portrayed as a human-headed bird. It could travel anywhere, and it represented the personality of the deceased. The akh represented the immortality of the deceased. It was free to dwell with the gods.
In order to make it to the delights of the afterlife, however, a dead spirit had to endure many trials. Its heart would be weighed by the god Thoth against the feather of truth. If the soul had done no evil, the heart would be lighter than the feather and the soul free to enjoy the delights of the Field of Reeds. If the soul had sinned, the heart would sink, and it would be snapped up by the vicious crocodile Ammit.
Mummies look good in white, since it sets off their naturally dark skin and eyes. They should avoid harsh skin cleansers and remember to always, always moisturize.