Longlining is a commercial and recreational fishing technique that uses heavy fishing line with baited hooks attached at intervals by means of branch lines called snoods. A snood is a short length line which is attached to the main line using a clip or swivel, with the hook at the other end. This is very similar to trotline fishing, except that entire rig is in the water - start and end of main line is anchored by means of more or less heavy weights on sea floor.
Longlines can be set to hang near the surface (pelagic longline) or along the sea floor (demersal longline). Longlines with traps attached rather than hooks can be used for crab fishing.
Recreational longline fishing is legal in many countries, but with limitations regarding fishing area, fishing season, number and size of hooks, entire length etc.