A diffusion pump is a type of vacuum pump that uses high-speed jets of vapor to create a vacuum. It operates by heating a fluid, usually oil, which then vaporizes and is directed through a nozzle. The vapor collides with gas molecules in the chamber, pushing them down into a lower pressure area, effectively removing them from the system. These pumps are commonly used in applications requiring high vacuum levels, such as in electron microscopy and mass spectrometry. They are efficient and can achieve pressures as low as 10^-10 torr, making them essential in various scientific and industrial processes.