cantilever

thumb|A schematic image of three types of cantilever. The top example has a full moment connection (like a horizontal flagpole bolted to the side of a building). The middle example is created by an extension of a simple supported beam (such as the way a Springboard|diving board is anchored and extends over the edge of a swimming pool). The bottom example is created by adding a [[Robin boundary condition to the beam element, which essentially adds an elastic spring to the end board. The top and bottom example may be considered structurally equivalent, depending on the effective stiffness of the spring and beam element.]]

A cantilever is a structural element that is firmly attached to a fixed structure at one end and is unsupported at the other end. Sometimes it projects from a vertical surface such as a wall. A cantilever can be in the form of a beam, plate, truss, or slab.