A clothes line or washing line is any type of rope, cord, or twine that has been stretched between two points (e.g. two sticks), outside or indoors, above the level of the ground. Clothing that has recently been washed is hung along the line to dry, using clothes pegs or clothes pins. Washing lines are attached either from a post or a wall, and are frequently located in back gardens, or on balconies. Longer washing lines often have props holding up sections in the middle due to the weight of the clothing.

More elaborate rotary washing lines save space and are typically retractable and square or triangular in shape, with multiple lines being used (such as the Hills Hoist from Australia). Some can be folded up when not in use (although there is a hazard of getting fingers caught, so there is usually a safety button).

In Scotland, many tenement buildings have a drying green which is a communal area predominantly used for clothes lines - it may also be used as a recreational space.