A proof of space-time (PoST) is a proof that shows the prover has spent an amount of time keeping the reserved space unchanged. Its creators reason that the cost of storage is inextricably linked not only to its capacity, but to the time in which that capacity is used. It is related to a proof-of-storage (but without necessarily storing any useful data), although the Moran-Orlov construction also allows a tradeoff between space and time.[7]