Knot

A knot is a way of fastening something long and thin like rope, string or yarn by tying or interweaving. You tie your shoelaces with a knot, and if you want to tie your dog to a pole by his lead so he can't run away, you use a knot for that too.

A bow is a special kind of pretty knot that leaves two big loops, and is usually made of ribbon in hair ties or on a dress.