Cleaning is the process of removing unwanted substances, such as dirt, infectious agents, and other impurities, from an object or environment. Cleaning is often performed for aesthetic, hygienic, functional, safety, or environmental protection purposes. Cleaning occurs in many different contexts, and uses many different methods. Several occupations are devoted to cleaning.

Ultrasonic cleaning is a process that uses ultrasound to agitate a fluid, with a cleaning effect. Ultrasonic cleaners come in a variety of sizes, from small desktop units with an internal volume of less than 0.5 litres (0.13 US gal), to large industrial units with volumes approaching 1,000 litres.