Half-hitches are great knots, but only when use in combination with other knots. By itself, a half-hitch is unsafe and unreliable, but when joined with other knots, can be quite the opposite. Tying two half hitch knots together is great for attaching a rope or line to any object. The half hitch and double half hitch are used throughout specialities, most notably as a boating knot, outdoor knot, and paddling knot.
Although the half hitch is knot in its own right, it is rarely used alone. Two half hitches can be use to tie a rope to a tree, boat or other object. It is often used in a supporting role, for example to increase the security of a primary knot. See how to tie both the single half hitch and the double.