A rig is an arrangement of items used for fishing. It can be assembled of one or more lines, hooks, sinkers, bobbers, swivels, lures, beads, and other fishing tackle. A rig might be held by a rod, by hand, or attached to a boat or pier. Some rigs are designed to float near the surface of the water, others are designed to sink to the bottom. Some rigs are designed for trolling. Many rigs are designed especially for catching a single species of fish.