The bucket has an inner volume as compared to other types of machine attachments like blades or shovels.
The bucket could be attached to the lifting hook of a crane, at the end of the arm of an excavating machine, to a the wires of a dragline excavator, to the arms of a power shovel or a tractor equipped with a backhoe loader or to a loader, or to a dredge.
The name bucket may have been coined from buckets used in water wheels, or used in water turbines or in similar-looking devices.
They can can be quite large like those equipping Hulett cranes, used to discharge ore out of cargo ships in harbours or very small such as those used by deep-sea exploration vehicles.
The shape of the bucket can vary from the truncated conical shape of an actual bucket to more more scoop-like or spoon-like shapes akin to water turbines. The cross section can be round or square.
An helicopter bucket allows to carry water above a fire site.
Excavator buckets are made of solid steel and generally present teeth protruding from the cutting edge, to disrupt hard material and avoid wear-and-tear of the bucket.
The clamshell bucket is a more sophisticated articulated several-pieces device, including two elementary buckets associated on a hinged structure forming a claw-like appendage with an internal volume.
The bucket wheel design is also used to capture the water energy in water-wheels or water turbines like Pelton wheels. The buckets also have to be made of solid material to withstand the the force of the water flow. Their shape is optimized according to their purpose.
Other designs include vertical shaft wind turbines designs like on the Savonius wind turbine. In this case, the buckets have to be made of a light material.
The buckets-ladders are used in bucket elevators or in the dredge design of some dredgers.