An item or equipment used for a specific purpose. A tool can be a physical object such as mechanical tools including saws and hammers or a technical object such as a web authoring tool or software program. Furthermore, a concept can also be considered a tool.
"Creativity is the tool which allows a child's mind to grow."
One can classify tools according to their basic functions:
Cutting and edge tools, such as the knife, sickle, scythe, hatchet, and axe are wedge-shaped implements that produce a shearing force along a narrow face. Ideally, the edge of the tool needs to be harder than the material being cut or else the blade will become dulled with repeated use. But even resilient tools will require periodic sharpening, which is the process of removing deformation wear from the edge. Other examples of cutting tools include gouges and drill bits.
Moving tools move large and tiny items. Many are levers that give the user a mechanical advantage. Examples of force-concentrating tools include the hammer which moves a nail or the maul which moves a stake. These operate by applying physical compression to a surface. In the case of the screwdriver, the force is rotational and called torque. By contrast, an anvil concentrates force on an object being hammered by preventing it from moving away when struck. Writing implements deliver a fluid to a surface via compression to activate the ink cartridge. Grabbing and twisting nuts and bolts with pliers, a glove, a wrench, etc. likewise move items by applying torque (rotational force).
Tools that enact chemical changes, including temperature and ignition, such as lighters and blowtorches.
Guiding, measuring and perception tools include the ruler, glasses, set square, sensors, straightedge, theodolite, microscope, monitor, clock, phone, printer.
Shaping tools, such as moulds, jigs, trowels.
Fastening tools, such as welders, rivet guns, nail guns, or glue guns.
Information and data manipulation tools, such as computers, IDE, spreadsheets
Some tools may be combinations of other tools. An alarm-clock is for example a combination of a measuring tool (the clock) and a perception tool (the alarm). This enables the alarm-clock to be a tool that falls outside of all the categories mentioned above.
There is some debate on whether to consider protective gear items as tools, because they do not directly help perform work, just protect the worker like ordinary clothing. They do meet the general definition of tools and in many cases are necessary for the completion of the work. Personal protective equipment includes such items as gloves, safety glasses, ear defenders and biohazard suits.