A jib or jib arm is the horizontal or near-horizontal beam used in many types of crane to support the load clear of the main support. Usually jib arms are attached to a vertical mast or tower or sometimes to an inclined boom.

In other jib-less designs such as derricks, the load is hung directly from a boom which is often anomalously called a jib. Bridge cranes and gantry cranes can move on three axes, two perpendicular axes and one vertical, for a versatile operational range.