Also called the Alpine Butterfly, this loop is strong, secure, and easily untied after being put under strain. It's a great loop for use anywhere along a rope, and holds well even with strain put on both standing parts.
1 Twist the rope twice to make two adjacent crossing turns.
2 Pull down the outer turn.
3 Bring the middle of the loop up through the center of the other crossing turn.
To tighten the loop, pull on all the leads. As you can see, the Butterfly Loop ties very quickly with just a little practice.