A hand plane is a tool for shaping wood using muscle power to force the cutting blade over the wood surface. Some rotary power planers are motorized power tools used for the same types of larger tasks, but are unsuitable for fine-scale planing, where a miniature hand plane is used.

Generally, all planes are used to flatten, reduce the thickness of, and impart a smooth surface to a rough piece of lumber or timber. Planing is also used to produce horizontal, vertical, or inclined flat surfaces on workpieces usually too large for shaping, where the integrity of the whole requires the same smooth surface. Special types of planes are designed to cut joints or decorative mouldings.

Hand planes are generally the combination of a cutting edge, such as a sharpened metal plate, attached to a firm body, that when moved over a wood surface, take up relatively uniform shavings, by nature of the body riding on the 'high spots' in the wood, and also by providing a relatively constant angle to the cutting edge, render the planed surface very smooth. A cutter that extends below the bottom surface, or sole, of the plane slices off shavings of wood. A large, flat sole on a plane guides the cutter to remove only the highest parts of an imperfect surface, until, after several passes, the surface is flat and smooth. When used for flattening, bench planes with longer soles are preferred for boards with longer longitudinal dimensions. A longer sole registers against a greater portion of the board's face or edge surface which leads to a more consistently flat surface or straighter edge. Conversely, using a smaller plane allows for more localized low or high spots to remain.

Though most planes are pushed across a piece of wood, holding it with one or both hands, Japanese planes are pulled toward the body, not pushed away.

Woodworking machinery that perform a similar function as hand planes include the jointer and the thickness planer, also called a thicknesser; the job these specialty power tools can still be done by hand planers and skilled manual labor as it was for many centuries. When rough lumber is reduced to dimensional lumber, a large electric motor or internal combustion engine will drive a thickness planer that removes a certain percentage of excess wood to create a uniform, smooth surface on all four sides of the board and in specialty woods, may also plane the cut edges.

Hand planes are ancient, originating thousands of years ago. Early planes were made from wood with a rectangular slot or mortise cut across the center of the body. The cutting blade or iron was held in place with a wooden wedge. The wedge was tapped into the mortise and adjusted with a small mallet, a piece of scrap wood or with the heel of the user's hand. Planes of this type have been found in excavations of old sites as well as drawings of woodworking from medieval Europe and Asia. The earliest known examples of the woodworking plane have been found in Pompeii, although other Roman examples have been unearthed in Britain and Germany. The Roman planes resemble modern planes in essential function, most having iron wrapping a wooden core top, bottom, front and rear, and an iron blade secured with a wedge. One example found in Cologne has a body made entirely of bronze without a wooden core. A Roman plane iron used for cutting moldings was found in Newstead, England. Histories prior to these examples are not clear, but furniture pieces and other woodwork found in Egyptian tombs show surfaces carefully smoothed with some manner of cutting edge or scraping tool. There are suggestions that the earliest planes were simply wooden blocks fastened to the soles of adzes to effect greater control of the cutting action.

In the mid-1860s, Leonard Bailey began producing a line of cast iron-bodied hand planes, the patents for which were later purchased by Stanley Rule & Level, now Stanley Black & Decker. The original Bailey designs were further evolved and added to by Justus Traut and others at Stanley Rule & Level. The Bailey and Bedrock designs became the basis for most modern metal hand plane designs manufactured today. The Bailey design is still manufactured by Stanley Black & Decker.^{[citation needed]}

In 1918 an air-powered handheld planing tool was developed to reduce shipbuilding labor during World War I. The air-driven cutter spun at 8,000–15,000 rpm and allowed one man to do the planing work of up to fifteen men who used manual tools.