As the name implies, an animal's lead rope, attached to its halter, may be tied to a post or hitching rail with this knot.
The benefit of the halter hitch is that it can be easily released by pulling on one end of the rope, even if it is under tension.
Some sources show the knot being finished with the free end running through the slipped loop to prevent it from working loose or being untied by a clever animal, still allowing easy but not instant untying.
[1][2] The halter hitch can be derived from the Noose knot by turning the working end into a bight.
[3] The falconer has to tie the same knot one handed, throwing the end around the anchor object (the perch), gripping it with a scissoring fingers act, pulling the bight from opposite side of the main part using the back of the thumb.