Mummies of humans and other animals have been found throughout the world, both as a result of natural preservation through unusual conditions, and as cultural artifacts to preserve the dead. There are more than 1000 mummies in dry Xinjiang China. Over one million animal mummies have been found in Egypt, many of which are cats. There are so called mummies of mythical beings.

The English word mummy is derived from medieval Latin mumia, a borrowing of the Persian word mūm (موم), which means "bitumen". Because of the blackened skin bitumen was once thought to be used extensively in ancient Egyptian embalming procedures. (See also: Mummia.)

Of special interest are finds that may testify to the beliefs of the Ancient population of Egypt. In two Neolithic cemeteries, skulls were found that indicated tooth replacement in antiquity. In both cases, the teeth were apparently collected and repositioned by Neolithic people after being disturbed by later burials. Also in the same cemetery, four bracelets were found encircling a right humerus, which had been moved from its original anatomical position during the deposition of a later burial. However, the bracelets were maintained in place by the insertion of the individual’s own right ulna and radius that had been fractured post-mortem. Such manipulation suggests that the intention was to repair the damage caused during the insertion of later interments. These intentions are supported by the discoveries, of two skulls with mis-positioned teeth. In one case, the right orbit contained eighteen of the individual’s teeth; in the other, the nasal aperture contained one tooth.

All of these examples suggest a deep conviction about the importance of body preservation, i.e., keeping it together, ideally in an undisturbed state. Perhaps this was necessary to secure eternal life––similar to the belief that is so popular throughout all of ancient Egyptian civilization.

The earliest known Egyptian mummy , nicknamed 'Ginger' for its hair colour, dates back to approximately 3300 BC. Currently on display in the British Museum, Ginger was discovered buried in hot desert sand. Desert conditions can naturally preserve bodies so it is uncertain whether the mummification was intentional or not. However, since Ginger was buried with some pottery vessels it is likely that the mummification was a result of preservation techniques of those burying him. Stones might have been piled on top to prevent the corpse from being eaten by jackals and other scavengers and the pottery might have held food and drink which was later believed to sustain the deceased during the journey to the afterlife.

From the Middle Kingdom onwards, embalmers used salts to remove moisture from the body. The salt-like substance natron dried out and preserved more flesh than bone. Once dried, mummies were ritualistically anointed with oils and perfumes. The emptied body was then covered in natron, to speed up the process of dehydration and prevent decomposition. Natron dries the body up faster than desert sand, preserving the body better. Often finger and toe protectors were placed over the mummy's fingers and toes to prevent breakage. They were wrapped with strips of white linen that protected the body from being damaged. After that, they were wrapped in a sheet of canvas to further protect them. Many sacred charms and amulets were placed in and around the mummy and the wrappings. This was meant to protect the mummy from harm and to give good luck to the Ka of the mummy. Once preserved, they were laid to rest in a sarcophagus inside a tomb, where it was believed that the mummy would rest eternally. The mummy's mouth would later be opened in a ritual designed to symbolize breathing, giving rise to legends about revivified mummies. In some cases, a mummy has been discovered in an unmolested tomb, only to be found in a state of advanced decomposition due to the proximity of the water table. This was the case with the discovery in 1998 of the mummy of Iufaa, an Egyptian priest and administer who lived around 500 BC.

Mummies were much sought-after by museums worldwide in the 19th and early 20th centuries and many exhibit mummies today. Notably fine examples are exhibited at the Egyptian Museum in Cairo, at the Ägyptisches Museum in Berlin, and at the British Museum in London. The Egyptian city of Luxor is also home to a specialized Mummification Museum. The mummified remains of what turned out to be Rameses I ended up in a Daredevil Museum near Niagara Falls on the United States–Canada border; records indicate that it had been sold to a Canadian in 1860 and exhibited alongside displays such as a two-headed calf for nearly 140 years, until a museum in Atlanta, Georgia, which had acquired the mummy along with other artifacts, determined it to be royal and returned it to Egypt's Supreme Council of Antiquities. It is currently on display in the Luxor Museum.

Modern scientific methods are being applied to mummies for archeological research. Mummies are studied without unwrapping them using CAT scan and X-ray machines to form a digital image of what's inside. They have been very useful to biologists and anthropologists, providing a wealth of information about the health and life expectancy of ancient people. In 2008, the latest generation CT scanners (64- and 256-slice Philips machines at the University of Chicago) were used to study Meresamun, a temple singer and priestess at the Temple of Amun whose mummy now resides at the Oriental Institute of Chicago. Mummies have also been used in medicine to calibrate CAT scan machines at levels of radiation that would be too dangerous for living people.

Scientists interested in molecular cloning the DNA of mummies have reported findings of analyzable DNA in an Egyptian mummy dating to circa 400 BC. Although analysis of the hair of Ancient Egyptian mummies from the Late Middle Kingdom has revealed evidence of a stable diet, Ancient Egyptian mummies from circa 3200 BC show signs of severe anaemia and hemolytic disorders.

Dr. Bob Brier of Long Island University has been the first modern scientist attempting to apply ancient Egyptian methods of mummification.