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A lathe is a common tool used in machining.

Machining is an occupation or hobby or a class of material-working processes that involves using a power-driven machine tool, such as a lathe, milling machine, or drill, to shape metal. Machining is a part of the manufacture of almost all metal products. Some plastic parts are machined. A person who specializes in machining is called a machinist.

A room, building, or company where machining is done is called a machine shop.

Most machining operations can be divided into those that remove metal from an item, and those that form metal in an item.

Often an unfinished workpiece will need to have some parts removed or scraped away in order to create a finished product. For example, a lathe is a machine tool that generates circular sections by rotating a metal workpiece, so that a cutting tool can peel metal off, creating a smooth, round surface. A drill or punch press can be used to remove metal in the shape of a hole. Other tools that may be used for various types of metal removal are milling machines, saws, and grinding tools. Many of these same techniques are used in woodworking.

Metal can be formed into a desired shape much more easily than materials such as wood or stone, especially when the metal is heated. A machinist may use a forging machine to hammer or mold a hot metal workpiece into a desired shape. Dies or molds may be used if the metal is soft enough, or under high pressures. A press is used to flatten a piece of metal into a desired shape.

More recent, advanced machining techniques include electrical discharge machining (EDM), electro-chemical erosion, plasma arc cutters, laser, or water jet cutting to shape metal workpieces.

As a commercial venture, machining is generally performed in a machine shop, which consists of one or more workrooms containing major machine tools. Although a machine shop can be a stand alone operation, many businesses maintain internal machine shops which support specialized needs of the business.

The inferior finish found on the machined surface of a workpiece may be caused by insufficient clamping, cutting conditions (speed) or perhaps an incorrectly adjusted or dull tool. It is evident by an undulating or irregular finish, and the appearance of waves on the surface.

Machining can be a hobby in itself, or it can be useful in pursuing other hobbies. For instance, more serious car restorers have home workshops with a range of machine tools. There are also individuals who start building up a home workshop with the idea of eventually building some project, such as maybe a miniature steam locomotive, but get sidetracked into building the machine tools themselves and their accessories. The home machine shop thus may end up being a satisfying hobby in itself. There are in fact at least four magazines that cater to this side of the hobby, Home Shop Machinist and Machinist's Workshop in the USA, and Model Engineer and Model Engineer's Workshop in the United Kingdom. Machinist's Workshop and Model Engineer's Workshop tend to be very project-oriented, while the other two tend to present a mix of projects, techniques, and theory. The book Machine Shop Trade Secrets by James Harvey has received excellent reviews from both hobby machinists and pro's alike.

• National Institute for Metalworking Skills Standards download page
• U.S. Department of Labor Bureau of Labor Statistics Occupational Outlook Handbook
• American Precision Museum—A museum that preserves historically important machine tools and helps to educate on the history of machine tools
• Machinist journal News, Case studies for machinists
• Modern Machine tools Machine tool Blog
• Home Shop Machinist & Machinist's Workshop Web site for the magazines