Handlining is often used in semi-technical canyons where the consequences of falling are minimal. A handline is a rope that you can hang onto with your hands while climbing up or climbing down a steep or slick section. Sometimes handlines are fixed, but sometimes you have to set your own. You can also "handline" a rappel rope by lowering yourself down the rappel rope with your hands instead of using a rappel device.
Often times we use handlines when going up a semi-technical slot canyon. The more-skilled person goes up first without a rope, then he secures the handline around his waist or behind his knee for the rest of the group to use when they climb up.
Handlining is much faster than rappelling or ascending.
Handlining is more dangerous than rappelling or ascending. It also requires good hand and upper body strength.