Yes, it's a string with knots. A fancy one has a hook in one end, but otherwise that's it. I used this for the first time with my hammock, Ticket to the Moon actually sells these as sets and I was foolish enough to buy one. It was a rope. With knots on it. Nothing more…

What this does is that it gives an easy way to attach things to other things and then to adjust the tightness of one of the things (still following me?). Loop it around a tree and another one around another tree and you can attach your hammock at different heights without opening or tying any new knots. I've also made the perfect travel clothesline with the same technique: it's about 2 meters long with knots every 7 cm or so and has a hook on one end that I bent out of a small nail. I actually made two and looped them on to each other to make one longer clothesline with hooks on both ends. Even the simplest of hostels have always had two points where I can attach this to. As an added bonus, when there's enough weight on the line, you can put your clothes through the loops between the knots and the string itself acts as a clothespin. Finally, my latest design was attaching about 60 cm of similarly tied string on the top of our mosquito net. With a carabiner added it can be looped around objects such as a ceiling fan without tying any knots and you can also adjust the height of the thing.

How to make one:

You've probably figured it out already, but here it is anyway: take a rope or a string the strength you need and about 2.5 times as long as you want it to turn out in the end. Fold it from the middle, then tie the loose ends together with a simple knot. Make more knots at suitable interfaces as you go up the rope. You're done.

Silly as it may be, the hammock ropes and the clothesline have seen constant use over this trip. I find tying new knots all the time very annoying and this small innovation has saved me from just that. It may not be much, but at least worth a blog post!