Hitches are basically a means of attaching rope or cordage to an object. The simple cow hitch is better known as the lanyard hitch. It is generally used to secure cordage or a rope to a post, an item of gear or some other object. This knot is similar to the clove hitch but instead of tying the two half-hitches in the same direction, they are tied in opposite directions. It is a very simple and basic knot.
There is a variant of the cow hitch that is easily tied and can create a more secure knot. This variant is known as the bull hitch. It is simple and easy to learn to tie and will give you a more secure knot.
By simply twisting the top loop of your cow hitch and feeding the end of your lanyard back through the loop you create a bull hitch. When tightened properly, it gives you a very secure lanyard connection to your gear. It's important to remember that keeping your gear properly secured in any situation is critical.
My personal preference is to use a bull hitch for attachment of the leg tie-down on the scabbard of my Mora. This insures a good snug fit for the scabbard of my knife when tied off.
A great resource for learning how to tie a variety of knots properly can be found at http://www.netknots.com/. They offer different sets of knot cards at a very reasonable price. The knot cards can be easily carried and used for reference purposes to insure your knots are being tied properly.
Got survival knots?
Staying above the water line!
Riverwalker