A rivet is a permanent mechanical . Before being installed, a rivet consists of a smooth shaft with a head on one end. The end opposite to the head is called the tail. On installation, the rivet is placed in a punched or drilled hole, and the tail is upset, or bucked (i.e., deformed), so that it expands to about 1.5 times the shaft diameter, holding the rivet in place. In other words, pounding creates a new "head" on the other end by smashing the "tail" material flatter, resulting in a rivet that is roughly a dumbbell shape. To distinguish between the two ends of the rivet, the head is called the factory head and the deformed end is called the shop head or buck-tail.
Because there is effectively a head on each end of an installed rivet, it can support loads. However, it is much more capable of supporting (loads perpendicular to the axis of the shaft).