Tools and machines have evolved a lot in the modern period. But the basic function of them had always been to assist in doing certain tasks. Simple machines in olden times reduced the tasks by changing the direction or magnitude of the force applied. Pulley, levers, wedges, screws and inclined planes are all machines of the simple type. Now the tools and machines have expanded their definitions. Many of them convert one form of energy to other forms, mostly in to mechanical energy. Some are electronic devices with less mobility. They have commercial, industrial and private uses. Many of such tools require technical knowledge for their applications.