The hitch is a very common knot. It is useful on its own or as a means to make other knots more secure (such as the Clove Knot). Use the hitch whenever you need to attach a rope or livestock to a tree/post.
Make a loop around the post/tree, wrap the bitter end around the working end and make a loop. This knot is not very secure on its own.
Make more secure by adding additional hitches (of the same direction/handedness) on top of the first (shown on right).