Any kind of rope that can latch on or attach to a target, allowing the the user to:

* hang from the target or follow it
* pull themselves towards the object
* pull the object towards the themselves, like a frog's tongue

Usually has large claws or hooks on the end to grab to the top edge of a ledge or wall, like an anchor. 

In fantasy, they're the tools of assassins, spies, mercenaries, high-tech robots, and the military. They're often powered by gas, electricity, motors, magnets, and magic to pierce throw or really stick themselves to just about any target, even a flat wall and the heaviest of loose objects.