An autoclave (also called steam sterilizer) is a device that uses steam under pressure to disinfect instruments and other gear. The autoclave process kills dangerous bacteria and other micro organisms. “Autoclaving” can be called the “steam sterilization” process too.
There are many laws that govern the temperature and pressure for steam sterilizers. This is for patient and worker safety. Fully sterilized items will not infect wounds with bacteria or fungus contamination. They are also free of communicable diseases such as hepatitis, AIDS, etc.
Most autoclave machines have chambers that lock the contents inside during the sterilization cycle. The locking mechanism is to pressurize the chamber and its contents. They can be dangerous and have many different safety features. One is pressure monitoring and pressure release valves.
When an autoclave is running a cycle, it pressurizes, and basically becomes a tightly controlled bomb! If the sensor or valve comes under too much pressure, steam is vented out.
I have a breakdown of the different types of autoclaves on my front page (here).