Parachute Cord also known as Paracord was developed for just what the name implies. It started out being used by the Air Force to secure a jumpers Parachute to their harness. Paracord has since found it's way to many other uses.

The paracord I use has approximately a 400 pound breaking strength per strand; braiding increases the strength even more. Even with it's strength it has a very nice "handle" and feels quite nice in your hands. I have done some testing and it seems to have very good fade resistance.

Also one of it's best features is it's washable!! When it gets dirty just swash it around in some cold water and dish soap. Make sure you rinse it well, ring out the excess water and then hang to dry.

This is what Wikipedia has to say about Paracord.

Paracord was originally used in the suspension lines for parachutes. The kind used by the US military for this purpose is Type III, or #550 paracord. It is made of nylon, and consists of an outer jacket with seven braided inner threads. Only about 3/16 of an inch thick, it can support up to 550 lbs (under perfect test conditions). Paracord generally has very good strength for is thickness compared to other common kinds of rope, and because of its tough nylon construction, it is resistant to rot and abrasion.

There are various types of paracord, Type I, Type II, Type III and Type IV, with increasing roman numerals indicating increasing cord strength and an increasing number of inner braids which can be separated out of the main cord to be used in emergency situations as fishing line or sewing thread. Retrieved from http://en.wikipedia.org/wiki/Paracor