An angle grinder is a handheld tool powered by an electric motor or petrol engine. This drives a gearer head on which mounts an abrasive disc that can be renewed when worn. There are a myriad of different discs that are used for various materials and tasks, such as cutting discs, buffing pads and saws. The angle grinder has large bearings to counter side forces generated during cutting, unlike a power drill where the force is axial.
Used widely in Engineering, in particular metalworking and construction, as well as in emergency rescues. However, they can be very dangerous due to the high rpm involved and the sparks that fly off as they cut. Safety equipment should always be worn while using these or any power tools.
Contrast with Grinding machine and Bench grinder.