Prosciutto is made from high-quality pork legs. The meat is covered in salt and left to rest for a few weeks. During this time, the salt draws out blood and moisture, which prevents bacteria from entering the meat (and is why it's safe for us to eat it "raw"). Salting the meat also causes the flavors to become more concentrated.
After the salting process, the pork legs are washed, seasoned by hand (often according to a secret family recipe), and left to dry-age at a controlled temperature for 14 to 36 months. It is the combination of salt, air, and time that gives prosciutto its sweet and delicate flavor.