The Reef Knot, also known as the Square Knot, is a type of binding knot used to secure two ropes or lines together. It is formed by tying two overhand knots in opposite directions, creating a flat and symmetrical structure. This knot is commonly used in various applications, including sailing, camping, and first aid, due to its simplicity and effectiveness. While the Reef Knot is easy to tie and untie, it is important to note that it is not suitable for all situations. It can slip or come undone under heavy load or when the ropes are of different sizes. For more secure applications, other knots like the Bowline or Clove Hitch may be preferred.