This rod is designed to hold eight pounds of stress and no more. Heavy rods are designed to be just a bit softer than a pool cue. Extra-Heavy rods are pool cues with eyes. Designed to bring big fish out of heavy cover or grass. The tip or action is of the rod is also important.
Most rods are available in extra fast, fast, moderate and slow.
This addresses where the rod flexes. Moderate action will flex in the top half of the rod, and slow action will flex from the handle or the first eye up. Those signify the backbone of the tip. If you want to drive the hook through a 10-inch worm and penetrate more than skin, you don't need a rod with a weak tip. On the other hand, if you don't want to pull the hook out of a crankbait fish when it jumps you need a rod that will give when the fish jumps or shakes its head.