Dock lines are strong ropes used to secure a boat or ship to a dock or pier. They help keep the vessel stable and prevent it from drifting away due to wind or currents. Typically made from durable materials like nylon or polyester, dock lines come in various lengths and thicknesses to accommodate different sizes of boats. When tying a boat to a dock, it's important to use proper knots, such as the cleat hitch or bowline, to ensure the lines hold securely. Regularly checking the condition of dock lines is essential for safety, as worn or frayed lines can lead to accidents or damage to the vessel.