In its most basic form the autoclave is a pressure cooker. Water is heated in a pressurized environment to create steam. Using pressure makes it possible to heat to higher temperatures with less energy. Autoclaves are usually made of steel and have various configurations for removing air prior to pressurization. Downward displacement autoclaves use gravity to remove air. Steam pulsing autoclaves use pulses of steam along with pressurizing and depressurizing to reach optimum pressure. Vacuum pump autoclaves suck air out for pressurization. Superatmospheric autoclaves are a combination of steam pulsing and vacuum pump techniques.Autoclaves are widely used in microbiology, medicine, tattooing, body piercing, veterinary science, mycology, dentistry, chiropody and prosthetic fabrication.