The use of knots and ropes is a skill that if not properly understood and performed, can result in serious injury or death under the right circumstances.
There are many purposes or applications for knots, therefore certain qualities were sought after to meet the requirements of the task at hand. Many knots have been invented as a result, and I'll list some of the qualities that were sought after, and there are many more.
2. Ease of use such as being able to easily untie a knot that was under tension.
3. Strength of the knot. It must not slip when under strain.
4. Aesthetics. This isn't important in a survival situation of course.
5. Joining ropes, including ropes of different diameters.
6. Quick Release knots such as the Mooring Hitch.
I'll list some popular knots here below that can be used in a survival situation.
1. Bowline (in the photo above). Have a look at the Bowline on a Bite to.
2. Prusik. Have a look at the Klemheist to.
3. Clove Hitch. Have a look at the Constrictor knot to.
4. The Alpine Butterfly (photo below)
5. Double Overhand and Figure-8 Stopper Knots
6. The Mooring Hitch. It is a quick release knot and is good for more than mooring a boat to a dock.
I'll quote a portion of a paragraph from the Modern Cordage page. "Never unnecessarily cut a rope, and be aware that knots can weaken the rope by 50% of the rated strength, up to 80% with other ropes and knots"
Remember that the type of material used in the construction of the rope among other factors, will have an effect on the resulting quality of the knot.
There are different strengths and weaknesses with various knots. Not all ropes are suited for every knot. I the photo above you see The Alpine Butterfly knot.
Here is a non-exhaustive list of things that ropes can be used for. Of course different diameters have their benefits as well.
1. Shelter construction, such as lashings and tie points to hold a tarp up etc.
2. Climbing. Be certain to be properly trained for this as it involves specialized techniques and equipment.
3. Repairing clothing, or even making a belt for your pants or to hold a poncho around your waist.
4. Lanyards for knives, whistles and other very important items.
5. Fishing line and fishing nets.
6. Traps and snares for hunting.
7. Replacing shoe or boot laces.
8. Making a bow drill.
This page gives some general information on the subject of knots. Do some more research to learn more, because it is good to know some knots for the reasons mentioned above, such as safety etc.
Here are some links to help you learn more about knots.
Have a look at the Videos page as well for more information on the subject.