What are three ways a body can be mummified?

Bodies can be mummified in the Egyptian tradition by taking out the internal organs (which the Egyptians stored separately in jars) and letting the body dry out. A more modern technique is to saturate the body with formaldehyde, which is a powerful preservative (but also very toxic and carcinogenic, so while you can preserve bodies with it, you would not preserve food with it). An even more sophisticated technique is to freeze dry the body. In a vacuum, it will lose moisture even at low temperature, so you can dry it out while it is too cold to decay.