A file is a metalworking

Metalworking

Metalworking is the process of working with metals to create individual parts, assemblies, or large scale structures. The term covers a wide range of work from large ships and bridges to precise engine parts and delicate jewelry. It therefore includes a correspondingly wide range of skills,...

 and woodworking

Woodworking

Woodworking is the process of building, making or carving something using wood.-History:Along with stone, mud, and animal parts, wood was one of the first materials worked by early humans. Microwear analysis of the Mousterian stone tools used by the Neanderthals show that many were used to work wood...

 tool

Tool

A tool is a device that can be used to produce an item or achieve a task, but that is not consumed in the process. Informally the word is also used to describe a procedure or process with a specific purpose. Tools that are used in particular fields or activities may have different designations such...

 used to cut

Cutting

Cutting is the separation of a physical object, or a portion of a physical object, into two portions, through the application of an acutely directed force. An implement commonly used for cutting is the knife or in medical cases the scalpel...

 fine amounts of material from a workpiece. It most commonly refers to the hand tool

Hand tool

A hand tool is a device for performing work on a material or a physical system using only hands. The hand tools can be manually used employing force, or electrically powered, using electrical current...

 style, which takes the form of a steel

Steel

Steel is an alloy that consists mostly of iron and has a carbon content between 0.2% and 2.1% by weight, depending on the grade. Carbon is the most common alloying material for iron, but various other alloying elements are used, such as manganese, chromium, vanadium, and tungsten...

 bar with a case hardened surface and a series of sharp, parallel teeth. Most files have a narrow, pointed tang

Tang (weaponry)

A tang or shank is the back portion of a tool where it extends into stock material or is connected to a handle as on a knife, sword, spear, arrowhead, chisel, screwdriver, etc...

 at one end to which a handle can be fitted.

A similar tool is the rasp

Rasp

A rasp is a tool used for shaping wood or other material. It consists of a point or the tip, then a long steel bar or the belly, then the heel or bottom, then the tang. The tang is joined to a handle, usually made of plastic or wood. The bar has sharp teeth...

. This is an older form, with simpler teeth.