Roped solo climbing or rope soloing is a way to climb with relative safety without a climbing partner.

Variations

• Roped solo free climbing refers to top roping on a fixed rope or to a traditional (aka trad) rope solo free climb.

• Rope solo aiding involves fixing the rope to an anchor and connecting yourself to the free end with either knots or one of the various modern devices designed for roped soloing. Then the pitch is led as a standard aid pitch would be led.

• Simul solo aid is a Speed climbing
  Speed climbing
  Speed Climbing is climbing in which speed is the ultimate goal. Speed Climbing is done on rocks, walls and poles...
  
   technique where two climbers aid climb at the same time on opposite ends of the same rope. While climbing they alternate between free, aid, soloing, and simul climbing depending on the situation.

Devices and Methods

The most basic method involves building a multidirectional anchor

Anchor (climbing)

In rock climbing, an anchor can be any way of attaching the climber, the rope, or a load to rock, ice, steep dirt, or a building by either permanent or temporary means...

 and attaching one end of the rope to that and then tying in to the other end. Then using two locking carabiners you attach a clove hitch

Clove hitch

A clove hitch is a type of knot. Along with the bowline and the sheet bend, it is often considered one of the most essential knots. A clove hitch is two successive half-hitches around an object. It is most effectively used as a crossing knot. It can be used as a binding knot, but is not...

 to each one about 10-20 feet of rope away from the anchor and another 20-40 feet away and be sure the carabiners are locked with the clove hitches on your climbing harness

Climbing harness

A climbing harness is a piece of equipment used in certain types of rock-climbing, abseiling or other activities requiring the use of ropes to provide access or safety...

 (These attachment points could be closer or farther apart depending on the convenient ledges or stances the particular route has and the ability of the leader). Then you lead the 10-20 feet until that first carabiner and clove hitch are tight with the anchor and you undo that clove hitch and tie a clove hitch 30-60 feet along the rope away from the anchor. Continue this process until you get to the end of the pitch. Then you build another multidirectional anchor, attach the rope to the anchor, untie from the end of the rope, rappel the pitch, tie into the bottom of the rope, climb back up as the second using clove hitches every 10-20 feet to protect a fall or prussik knots to ascend the rope.

Potential danger

Roped soloing is much less dangerous than free soloing but more dangerous than climbing with a partner. One problem is that in a fall, the attachment system is loaded in a way it wasn't designed for. Also, in case of an accident, sometimes there is no one to go for help. It can also be tedious, as the climber must ascend each section of rock twice: once to add the next belay anchor, then again after descending to remove the previous one, effectively traveling the route three times.