A garbage disposal unit or waste disposal unit is a device, usually electrically powered, installed under a kitchen sink

Kitchen sink

Kitchen sink is a term often used in the phrase everything but the kitchen sinkKitchen sink may also refer to:* A sink in a kitchen for washing dishes, vegetables, etc* Kitchen Sink, a 1989 short film by Alison Maclean...

 between the sink's drain

Drain (plumbing)

A drain is the primary vessel for unwanted water to be flumed away, either to a more useful area, funnelled into a receptacle, or run into the sewers as waste.-Waste versus re-circulated drains:...

 and the trap

Trap (plumbing)

In plumbing, a trap is a U-, S-, or J-shaped pipe located below or within a plumbing fixture. An S-shaped trap is also known as the S-bend invented by Alexander Cummings in 1775 but became known as the U-bend following the introduction of the U-shaped trap by Thomas Crapper in 1880. The new U-bend...

 which shreds food waste into pieces small enough—generally less than 2 mm (0.078740157480315 in)—to pass through plumbing

Plumbing

Plumbing is the system of pipes and drains installed in a building for the distribution of potable drinking water and the removal of waterborne wastes, and the skilled trade of working with pipes, tubing and plumbing fixtures in such systems. A plumber is someone who installs or repairs piping...

.

Garbage disposal units are widely used in North America

North America

North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

n households, but far less commonly used elsewhere.
The garbage disposal was invented in 1927 by John W.