If you know one knot (in my opinion), it should be the taught-line hitch. Creates a loop at the end of a rope that will hold its shape (the knot will “lock”) under load. However the knot can be manually slid up and down to adjust the rope length. Used to support MantisBot.
Two Half Hitches
Same as the taught-line but won’t lock and tightens (noose-style) under load. I often tie a line with a two half hitches at one end and a taught line at the other.
This is used to start and end the square lashing (see below)
Best way to join two beams (using rope) at a 90 degree angle.