is directly descended from ancient hand tools]]A tool or device is a piece of equipment which typically provides a mechanical advantage in accomplishing a physical task, or provides an ability that is not naturally available to the user of a tool. The most basic tools are simple machines. For example, a crowbar simply functions as a lever. The further out from the pivot point, the more force is transmitted along the lever. When particularly intended for domestic use, a tool is often called a utensil.Philosopher once thought that only humans used tools, and often defined humans as tool-using animals. But observation has confirmed that multiple species can use tools, including monkeys, apes, several corvid, sea otters, and others. Later, philosophers thought that only humans had the ability to make tools, until zoologists observed birds Selection of tool diameter by New Caledonian crows Corvus moneduloides, Jackie Chappell and Alex Kacelnik November 29, 2003 and monkeys The Throwing Mad
Source:
http://en.wikipedia.org/wiki/Tool