A mummy is simply a human being whose soft tissue has been preserved long after death. Ordinarily, when a person dies, the decomposition process reduces the body to a bare skeleton in a matter of months. The rate of decomposition is dependent on a number of factors, chiefly the nature of the surrounding environment. (In modern times, the decomposition process takes a little longer than it did in the past, due to all the preservatives we consume.)

In most environments, the first stages of decomposition begin within a few hours. In this initial stage, called autolysis, organs that contain digestive enzymes (the intestines, for example) begin to digest themselves.

Mummy Dearest
One common question about mummies is how they got such a peculiar name. The term "mummy" was applied by early Arabic travellers visiting Egypt. When the outsiders saw some mummies that had been coated with black resin material, they assumed the Egyptian embalming process involved dipping the bodies in bitumen, a dark, sticky component of tar. Based on this misconception, they dubbed the preserved bodies "mummies," after mummiya, the Arabic word for bitumen.
Autolysis is followed by putrefaction, the breakdown of organic matter by bacteria. In normal, temperate circumstances, putrefaction gets going about three days after death. Within a few months, the body is reduced to a skeleton. In hotter, more humid environments, this process is accelerated, because bacteria reproduce rapidly in such conditions. In colder, drier conditions, the process is slowed, because bacteria need heat and water to thrive (this is why we use refrigerators to preserve food). If the conditions are cold or dry enough, or if there isn't enough oxygen, the environment is so harsh that few bacteria can survive. In this case, the body will not fully decompose, possibly for thousands of years.

Could you really find a mummy in your backyard? Well, that all depends on where you live.

In nature, bodies have been preserved in the frozen ice of glaciers, the oxygen-depleted depths of peat bogs and the arid ground of the desert. The "Iceman" discovered in 1991 by tourists in the Italian Alps is one of the most amazing natural mummies. The 5,300-year-old corpse, found with perfectly preserved tools, died in a rocky hollow that quickly filled up with snow. Essentially, this created a natural freezer that preserved the body's tissues. This mummy has provided historians with a great deal of information about Europe's copper age, including representative technology, human health and tattooing practices.

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