What is a furling sail?

Furling a sail simply means to put the thing away after use. Sails are commonly folded and covered, or rolled into a tubular shape by an onboard mechanism. Many sailors prefer to remove the sail from the rigging entirely; in this case it is typically folded and bagged. Sails on larger vessels are typically left in place, while it is easier to remove sails from the rigs of smaller vessels.