Transient dock lines are often described as lines used when you are away from your regular slip or mooring. Usually constructed out of nylon and have spliced eyes ready for use when you tie-up. The part of the line that has an eye is typically passed around the cleat and the other end is adjusted on the boat. They come in many different lengths and diameters and in dozens of combinations thereof. Permanent dock lines are constructed from nylon as well but add protection near the cleat from chafing. Adding a protective sleeve or a snubber is a popular option.