all fasteners  rivets, bolts, studs, screws, and concrete  anchors are measured in terms of their grip range the total thickness of the material to be fastened under the head plus the necessary thread engagement, or set as in the case of concrete anchors and rivets

grades  the relative strengths between bolts nuts and some screws and rods 2, 5 , 8 , A -307, A325, A-490, B-7, B-16 , metrics 8.8. 9.8,10.9,12.9 and marked accordingly

threading  measured in threads per inch or pitch,  milimeters in the case of metrics