In English, screw or bolt is a method and means of connection that is spirally threaded and usually made of metal. Although in Farsi only the word screw is used for different types of this piece, in English they usually distinguish between Screw and Bolt.

Although there is no accepted difference between a BOLT and a SCREW, a BOLT usually refers to a bolt that passes through a hole and is locked on the other side with a nut, while a SCREW refers to a screw that usually They don’t have nuts. It closes by itself and is often used together with wood or plastic. In Persian language, sometimes SCREW is also called automatic screw.

A nut is a piece in the form of a round or polygonal ring whose hole is ribbed. Nuts are auxiliary fasteners for screws to tighten the screws in the direction of twisting. The so-called nut and screw are connected with the female and the male. The thread and ribs of the screw must have a special fit with the thread and ribs of the nut to cause the correct rotation of the screw inside each other. Nuts are usually made of steel, iron or other metals, but plastic nuts are also made for plastic screws.