A bolt is composed of a shank that is partially or fully threaded,and may or may not taper; and a head that is usually larger than the body of the bolt.Most bolts are driven into a material but there are exceptions.Bolts usually have right handed threads except where they can be subjected to anticlockwise forces.Bolts are made of metals-stainless steel alloys, titanium;or plastic-Teflonnylon.The shape of screw heads varies -panbuttonroundtruss flat, ovalbugleoctagonhexagoncheesefillister, mirror screw or headless.Drive designs onthe screw heads also vary-single slotcross-head, square, hex, Torx, Pozidriv,Supadriv,tri-wing,double hex,Bristol,combi-head drives and more.Common types of bolts or screws are:

coach screw

concrete screw 

deck screw

 dowel screw 

drywall screw

lag bolt

particle board screw 

screw eye

self-drilling screw

sheet metal screw 

wood screw

breakaway bolt

button socket cap screw 

carriage bolt 

cap screw

eye bolt

elevator bolt

 flange bolt

flat socket cap screws

 hex bolt

hex head cap screw 

machine screw 

metric flange bolt

self-tapping machine screw