A tool is any instrument that is used for making dimensional or material changes to any other objects. Actions carried out by cutting, shearing, grinding and measuring are accomplished with the help of tools. Tools are not just the traditional metallic objects shaped to perform special actions or mechanised gadgets; they could also refer to software programs that are used to test other big programs.
A hand tool is a manual instrument, usually made out of a drop forged alloy, operated by the muscular strength of the user. A machine tool is operated in dangerous environments to perform much the same functions, but with little involvement of human operators. Tools are the main means by which human beings, as well as animals can alter and control their immediate surroundings according to their needs.
The development of the tools by human beings is considered a crucial evolutionary step. Hammers, knives and axes were some of the earliest tools. Saw-like cutting blades were developed by the Neanderthal Man, a remarkable toolmaker. The Neolithic period, about 7000 years B.C., saw the development of the first metal tools. Iron and copper began to be used after smelting became common. At later stages and up to the Middle Ages tools such as drills, files, rulers, compasses and tongs became popular. The Industrial Revolution saw the emergence of new innovations in the making of different types of tools.
Machine-driven or machine tools became popular in the 19th and 20th century. There are several classes of machine tools. Important among them are: shapers and planers, power drills, grinding machines and hydraulic processes. The most popular machine tool used in the mechanical engineering industry is the lathe machine, which is employed in a vast number of tool operations during manufacturing processes.
Shapers and planers use single-point fittings. Power drills have spirals on their tools in order to bore through metal or wood. Countersinking, boring and tapping can be done with lathes. Milling and machine are used as abrasives. Power saws may use long thin moving belts or chains with levers to facilitate cutting. Automatic tools have great repeatability and accuracy. Computers are being rapidly brought in for controlling tools such as lathes. Computer numeric control is becoming increasingly popular in today's modern world.