The Half Hitch is very widely used fastening. It is, in fact, a single hitch formed around the standing part of another hitch. It is used to complete and strengthen other knots, as in the Round Turn and Two Half Hitches, which can then be used for tying, hanging, hooking objects etc. The Slipped Half Hitch is a useful variation of the Simple Half Hitch; a sharp pull on the working end releases the knot.
To Tie a Half Hitch Knot:
A Single Half Hitch is formed by taking the working end through a ring or similar object, back out over the standing part, and through the loop. Pull on the working end and the standing part to tighten.
To form Two Half Hitches take the working end around again, over the standing part and through the loop.
The Slipped Half Hitch is formed by placing a bight between the loop and the standing part; one sharp pull on the working end releases the knot.