A trotline is a variation of a setline. Webster's dictionary defines a setline as being "a long heavy fishing line to which several hooks are attached in series." A trotline is defined as "a comparatively short setline used near shore or along streams." Some other common variations of a setline include limblines, throwlines, and juglines. The Department of Game & Fisheries defines a trotline as "a line without a rod or reel attached that need not be held in the hand or closely attended."

A trotline is nothing more than a long line, resting on or close to the bottom and anchored at both ends, to which a series of baits are attached at intervals of two to three feet apart. The baits are attached to the main line by simple slipknots or by shorter lines called dropper lines (known as trots or snoods.)