The primary appeal of hammock camping for most users is comfort and better sleep, as compared to sleeping on a pad on the ground. Hammock camping enthusiasts argue that hammocks don't harm the environment in the way that conventional tents do. Most hammocks attach to trees via removable webbing straps, or "tree-huggers," which don't damage the bark and leave little or no marks afterward. Whereas it's easy to see a frequently used campground because of the effect on the grass, scrub and topsoil, the presence of a hammock camping site is much harder to detect. This has found favour with hikers and campers who follow the principles of Leave No Trace camping. Hammock camping also opens up many more sites for campers - stony ground, slopes, and so on - as well as keeping them off the ground and away from small mammals, reptiles and insects. Sleeping off the ground also keeps the camper out of any rainwater runoff that might seep in under a tent during a downpour. Lastly, the relatively light weight of hammocks makes them ideal for reducing backpack weight, thereby making it a good option for ultralight backpacking enthusiasts.