Granny knot its possible use tying the necks of grain sacks. When attempting to tie a reef knot (square knot), it is easy to produce a granny knot accidentally. This is dangerous because the granny knot can slip when heavily loaded. A tightened granny knot can also jam and is often more difficult to untie than the reef knot. It is better to tie a reef knot in nearly all circumstances. One way to distinguish them is that in the reef knot each loop passes completely over, or completely under (not through) the neck of the other. The reef knot is commonly
Overhand knot There are a number of ways to tie the Overhand knot. In heraldry, the overhand knot is known as a "Stafford knot", owing to a representation of it being used first as a heraldic badge by the Earls of Stafford, and later as a general symbol of Staffordshire. As a defensive measure, hagfishes, which resemble eels, produce large volumes of thick slime when disturbed. A hagfish can remove the excess slime, which can suffocate it in a matter of minutes, by tying its own body into an overhand knot, then sliding the knot from its head down to the tail.