A pencil sharpener is a device for sharpening a pencil

Pencil

A pencil is a writing implement or art medium usually constructed of a narrow, solid pigment core inside a protective casing. The case prevents the core from breaking, and also from marking the user’s hand during use....

's writing point by shaving away its worn surface. Pencil sharpeners may be operated manually or by an electric motor

Electric motor

An electric motor converts electrical energy into mechanical energy.Most electric motors operate through the interaction of magnetic fields and current-carrying conductors to generate force...

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Before the development of dedicated pencil sharpeners, a pencil was sharpened by whittling

Whittling

Whittling is the art of carving shapes typically out of raw wood or bone with a knife.Whittling is typically performed with a light, small-bladed knife, usually a pocket knife. Specialised whittling knives are available as well...

 it with a knife

Knife

A knife is a cutting tool with an exposed cutting edge or blade, hand-held or otherwise, with or without a handle. Knives were used at least two-and-a-half million years ago, as evidenced by the Oldowan tools...

. Pencil sharpeners made this task much easier and gave a more uniform result. Some specialized types of pencils, such as carpenter's pencils are still usually sharpened with a knife, due to their flat shape, though recently a fixed-blade device with a rotatable collar has become available.

Bernard Lassimone, a French mathematician, applied for the first patent (French patent #2444) on pencil sharpeners in 1828.