I made these beam hooks a little while back. Some people call them post hooks as well. Regardless, the reason behind their name is that they were traditionally used by hammering them into beams or posts in buildings. A lot of the old homes of the time were either timer framed or log construction, so these hooks could just be hammered into any place where they were needed. This saved the blacksmith from having to make nails to mount them. In the modern world they tend to get used in pole barns or log cabins. People will often hammer them into trees to hand things in their yards.
I made these from 3/8″ round stock. Then I hammered them into a square shape and drew out the ends. One has a single twist while the other has a double.