Rope can be strung up to climb down cliffs and shafts. To hang a rope, 右鍵 it on the tip of a Rock Spike, or on a Steel Rope Anchor. This ties off the rope and turns the block into an anchor.
右鍵 the rope again to throw it out in the direction you are facing, laying down rope that you can climb. To recall the rope, 右鍵 the anchor with an empty hand. The rope will be destroyed, the spike will turn back into an anchor, and the items returned to you.
Rock Spikes cannot be picked up, so the Steel Rope Anchor can be crafted and placed wherever you need an anchor instead.