The Harness Bend is a general purpose bend knot used to join two ropes together. The knot can be tied under tension and will not capsize.
The harness bend is essentially two half hitches each made by one of the two joined ropes, around the other ropes body. The ends get caught in between the two ropes and the two half hitches, at the elliptical eye in the middle of the knot.
There are two ways to tie this bend: type A with ends pointing in the same direction, and type B with ends pointing in opposite directions. The starting side of one of the half hitches has to be different, in order to have the ends approach the elliptical eye in the middle, from the prescribed direction.