The joint is the connection point in the middle of the cue. Most cues separate into two pieces for storage. The joint screws the shaft and butt together securely. A tight joint keeps the cue straight during play. If loose, it can affect accuracy. Materials vary, but strength is key. For example, a player assembles the cue before a match. They tighten the joint to ensure stability. A solid joint makes the cue feel like one single piece.