The overhand knot is a type of knot.

Canonical Name: Overhand knot.
Variant Name(s): Thumb knot; the equivalent in knot theory is called the trefoil knot.
Category: Stopper
Origin: Ancient
Related knots: blood knot, figure-of-eight
Releasing: Extreme jamming. This is the knot into which any line, twine, rope, garden hose or electrical cord will spontaneously evolve. Native Americans are said to have called the overhand knot "the knot that ties itself" from having found it formed by nature in plant tendrils and by "spontaneous composition" in tangled rope.
Efficiency: Unknown%
Load Strength: 50%
Caveat: Secure if wet.
Uses: Fishing, climbing, shoelaces, making other knots.
Comments: This is one of the fundamental knots, and forms the basis of many others including the simple noose , angler's loop, fisherman's knot, and blood knot. The overhand knot is very secure, to the point of over jamming. It should be used if the knot is intended to be permanent.
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, by twisting the hand over at the wrist and pinch the working end with your fingers and pull through the loop.