A rivet is a permanent mechanical fastener. Before it is installed it consists of a smooth cylindrical shaft with a head on one end. The end opposite the head is called the buck-tail. On installation the rivet is placed in a pre-drilled hole. Then the tail is "upset" (i.e. deformed) so that it expands to about 1.5 times the original shaft diameter and holds the rivet in place. To distinguish between the two ends of the rivet, the original 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 tension loads (loads parallel to the axis of the shaft); however, it is much more capable of supporting shear loads (loads perpendicular to the axis of the shaft). Bolts and screws are better suited for tension applications.

Fastenings used in traditional wooden boat building like copper nails and clinch bolts work on the principle of the rivet but they were in use long before the term rivet was invented and, where they are remembered, are usually classified among the nails and bolts respectively.

Types

There are a number of types of rivets, designed to meet different cost, accessibility, and strength requirements:

Solid rivets

Solid rivets are one of the oldest and most reliable types of fasteners, having been found in archaeological findings dating back to the Bronze Age. Solid rivets consist simply of a shaft and head which are deformed with a hammer or rivet gun. The use of a rivet compression or crimping tool can also be used to deform these type of rivets; this tool is mainly used on rivets closer to the edge since it is limited by its depth of frame. A rivet compression tool does not require two people and is generally the most foolproof way to install solid rivets. thumb|200px|left|Riveting team working on the cockpit shell of a C-47 transport at the plant of North American Aviation. The woman at left operates an air hammer, while the man at right holds a bucking bar Solid rivets are used in applications where reliability and safety count. A typical application for solid rivets can be found within the structural parts of aircraft. Hundreds of thousands of solid rivets are used to assemble the frame of a modern aircraft. Such solid rivets come with rounded (universal) or 100° countersunk heads. Typical materials for aircraft rivets are aluminium alloys (2017, 2024, 2117, 7050, 5056, 55000, V-65), titanium, and nickel based alloys (e.g. Monel). Some aluminum alloy rivets are too hard to buck and must be softened by annealing prior to being bucked. "Ice box" aluminum alloy rivets harden with age. These rivets are likewise annealed and then kept under sub-freezing refrigeration (hence the name "ice box") to slow the age hardening process. Steel rivets can be found in static structures such as bridges, cranes, and building frames.