Barb

The barb works by making the hook harder to reverse than it was to enter. It is why a fish that goes slack on the line usually stays hooked, and it is why removing a hook from a fish, or from your own thumb, is more involved than pushing it back the way it came.

Going barbless is a choice, not a purchase. Crimp the barb flat with pliers and the hook is barbless. Fly anglers and catch and release fisheries do this routinely, and some waters require it.

The cost is fewer landed fish, mostly on slack line, and the benefit is much faster, cleaner unhooking, which matters if you are releasing everything or fishing with kids. Keeping steady pressure through the fight closes most of that gap, because a barbless hook only backs out when the line goes slack.

Micro-barbs are a middle ground. Several makers now cut a barb small enough to hold a fish and still push back through flesh without tearing, and fly hooks in particular are often sold that way.