Forking is a technique for opening up, turning and loosening soil. As the tines can slide between stones more easily than a spade, they are particularly useful for stony and rocky ground. Forks are also good for clearing weeds from the soil, as they tend to remove the entire weed rather than leaving small, chopped pieces that may regenerate.
Forking is much less damaging to the soil structure than a spade as it breaks the clods up along their natural, existing fracture lines, rather than along artificially cut ones.