The Bowline is an incredibly useful knot. It provides a loop which won’t slip. This is used in a variety of settings, from mooring to attaching sheets to sails.
Instructions for the Bowline can be found here:
https://www.animatedknots.com/bowline-knothttp://www.animatedknots.com/
Looking for a way to create two loops? Take a look at Bowline on a Bight.
