Shank

Shank length changes what the hook is good at. A long shank gives you something to grip with pliers or a disgorger. That is the reason panfish hooks and Aberdeens are long: a bluegill that swallowed a worm is much easier to unhook when there is shank sticking out.

A short shank hides better inside a live bait and inside a small soft plastic, and it puts the hook point closer to the bait's profile so a fish takes the whole thing. Live bait and finesse patterns run short for that reason.

Shank thickness is a separate axis from length, described as light wire or strong wire, and shank shape can carry an offset kink for holding soft plastics. Some patterns also add a baitholder, which is a pair of small barbs cut into the shank to stop a worm sliding down.

Shank length is not part of the size number, so a size 6 Aberdeen and a size 6 octopus hook have very different shanks and fish quite differently. Read the pattern name as well as the size.