The beer knot is used to tie two pieces of tubular webbing together. When you're done, one tail ends up inside one strand while the other tail ends up outside the other strand. The Beer Knot is used to make homemade slings.
The beer knot is cleaner than the water knot. It also retains 80% of its strength.
The beer knot is difficult to inspect.
The beer knot can be untied in the field but has to be tied at home.