A slackline is, in its simplest form, a piece of webbing strung between two trees on which you try to balance. People begin by simply standing on a slackline, then learn to walk forwards and backwards, turn around, and do all kinds of tricks while balancing on the line. Most people do this close to the ground, but some people choose to do it high off the ground. Slacklining is quite different from walking a tightrope, because a slackline bounces and sways significantly depending on the length of the line and the amount of tension in the setup.

Slacklining began when climbers hanging out in campgrounds became bored and started playing with their equipment. Slacklining develops balance which is helpful in climbing, but that is not the only reason people do it. Far more important is the feeling you get when you experience that moment of perfect balance, when your mind and body are absolutely motionless over the line and all is right in the world.