A strong and simple knot that tightens when the end is seized as shown.
The Surgeon's Knot is a modified reef knot, and is usually used with twine. The extra turn in the first tie prevents slipping.
Also known as a Weaver's Knot, is used to join small or medium sized ropes.
A very useful knot for hoisting and towlines because it holds well and doesn't slip or jam.
The Fisherman's Knot is the strongest known method of joining fine lines such as fishing lines.
The figure-eight knot is used at the end of a rope to stop the strands from unraveling.
Also known as the Builder's Hitch because builders often use it to fasten staging to upright posts.
Reef Knot / Square Knot
If a square knot is used with ropes of unequal size, or if one rope is stiffer than the other, it WILL come undone. A square knot should NEVER be used to tie two ropes together (This is called a bend.) Many lives have been lost as a result of using a square knot to tie two ropes together.
This is by no means a complete or authoritative list. For the best list on the net with videos and step by step instructions of all the knots see Animated Knots