A file is a tool used for making a surface smooth, rounding off the corners and scraping off unwanted parts by rubbing against the material. It can be made of metal, paper or cloth. A file has a countless number of small teeth on its surface. This is referred to as the cut. There are various types of cuts in a wide range of roughness and smoothness. The appropriate type should be selected depending on the material it will be used on.

Metal files can be divided into those that are used for woodworking and those for metalworking. Depending on the characteristics of the cut, they can be single-cut, double-cut, rasp-cut, etc. Files are also categorized by their teeth into rough, medium, smooth, etc. For example, wood is generally shaped roughly with a rasp-cut file first, then in more detail with a single or double-cut file, and finally finished with sandpaper. Many of the metalworking files available on the market are double-cut files.

Paper and cloth-type products that are made by coating the substrate sheet with abrasive are referred to as sandpaper, emery paper, abrasive paper, etc. Fine grit sandpaper and wet and dry sandpaper are often used for the finish. In addition to these, there are also board rasps which have rough teeth resembling a grater used for grinding plaster boards and Styrofoam, needle files and super fine files which are used for scoring fine details into metal and glass, and files used specifically for sharpening saws.

When using a woodworking or metalworking file, the material should be fixed firmly in place with a vise or by hand. If the object is too small to secure, it is also possible to hold the file steady and rub the object against it. The grain on sandpaper and emery cloth is not aligned in a particular direction, but the teeth on metalworking and woodworking files are positioned so that they grind when the files are pushed forward. If the teeth get clogged with shavings, they must be dusted off with a brush. Various types of files can be obtained at home centers and hardware stores.