The overhand knot is one of the most fundamental knots and forms the basis of many others including the simple noose

Noose

A noose is a loop at the end of a rope in which the knot slides to make the loop collapsible. Knots used for making nooses include the running bowline, the tarbuck knot, and the slip knot.-Use in hanging:...

, overhand loop

Overhand loop

The Overhand loop is a simple knot which forms a fixed loop in a rope. Made by tying an Overhand knot in the bight, it can be tied anywhere along a rope . The knot can be used for attaching clips, hooks, other rope, etc., but has the disadvantage that it is likely to jam tight when the rope has...

, angler's loop

Angler's loop

An Angler's loop is a type of knot which forms a fixed loop. Useful for fine or slippery line, it is one of the few loop knots which holds well in bungee cord. It is quite secure but it jams badly and is not suitable if the knot will need to be untied...

, reef knot

Reef knot

The reef knot or square knot is an ancient and simple binding knot used to secure a rope or line around an object. Although the reef knot is often seen used for tying two ropes together, it is not recommended for this purpose due to potential instability of the knot.A reef knot is formed by tying...

, fisherman's knot

Fisherman's knot

The fisherman's knot is a bend with a symmetrical structure consisting of two overhand knots, each tied around the standing part of the other...

 and water knot

Water knot

The water knot is a knot frequently used in climbing for joining two ends of webbing together, for instance when making a sling.-Tying the water knot:...

. The overhand knot is very secure, to the point of jamming badly. It should be used if the knot is intended to be permanent. It is often used to prevent the end of a rope from unraveling.

Tying

There are a number of ways to tie the Overhand knot.

• Thumb method - create a loop and push the working end through the loop with your thumb.
• Overhand method - create a bight
  Bight (knot)
  In knot tying, a bight is a curved section, slack part, or loop between the two ends of a rope, string, or yarn. The term is also used in a more specific way when describing Turk's head knots, indicating how many repetitions of braiding are made in the circuit of a given knot.-Slipped knot:In order...
  
  , by twisting the hand over at the wrist and sticking your hand in the hole, pinch the working end with your fingers and pull through the loop.

Knot theory

If the two loose ends of an overhand knot are joined together (without creating additional crossings), this becomes equivalent to the trefoil knot

Trefoil knot

In topology, a branch of mathematics, the trefoil knot is the simplest example of a nontrivial knot. The trefoil can be obtained by joining together the two loose ends of a common overhand knot, resulting in a knotted loop...

 of mathematical knot theory

Knot theory

In topology, knot theory is the study of mathematical knots. While inspired by knots which appear in daily life in shoelaces and rope, a mathematician's knot differs in that the ends are joined together so that it cannot be undone. In precise mathematical language, a knot is an embedding of a...

.

Overhand knot in paper-folding

If a flat ribbon or strip is tightly folded into a flattened overhand knot, it assumes a regular pentagonal shape.