It's as important to know when, where and why to use the right knot as it is to know the knot. The
bowline is the king of knots, but it can't be tied or untied under strain .
Sheet bends and
clove hitches can be tied but not untied under a lot of strain, but attach lines to other lines very well, parallel and perpendicular respectively. They both bind often, as well. As a commercial
fisherman, one of the best general knots I have ever found is the
munter knot (I only heard it called that once, it may have another name or three). This
knot will not attach well to another line but works well on any standing object, can be drawn up and let out under strain, and never, ever, ever binds. Tie it this way- take a half bend around your standing object (rail, piling, skipper, etc.) Then take a half bend around the standing line, where it first contacts your object. Bring your line back around your object. This is the brilliant part of the knot- right here you can hold as much weight with two fingers as the line can take, as well as let out or take in line. The half bend around the standing line creates a bridle which cannot bind. All that's left to make it fast is a couple of
half hitches onto the standing line. I heard you can use this minus the half hitches to
belay, which makes a lot of sense.