PoST stands for Proof-of-Spacetime (PoST) - a consensus algorithm closely related to proof-of-capacity (PoC).
The existence of financially incentivized participants who will take part in the network honestly and not benefit from harming the network is a prerequisite for both PoST and PoC to be functional. What’s different is that PoST allows network participants to show that they have been physically storing data (spent a "spacetime" resource/allocated storage capacity to the network) over a certain period of time. “Spacetime” can be described as filling a specified amount of storage for a specified period. During the said period, the storage cannot be used for anything else.
Participants preferring storage over computing, which is much less energy-consuming, is key to the PoST consensus algorithm. Another instrumental element here is rationality, which refers to the rational preference of participants to opt for storage instead of computing as this way, they minimize their costs and maximize their profits.
Simply put, PoST means that participants can guarantee and prove that they are spending a certain amount of space for storage.
According to the PoST creators, Tal Moran and Ilan Orlov, this is called the “'Rational' Proofs of Space-Time because the true cost of storage is proportional to the product of storage capacity and the time that it is used.” Moran and Orlov have come up with this new consensus algorithm, hoping to create an alternative to the popular but energy-guzzling Proof-of-Work (PoW) mechanism.
Participants are required to demonstrate a financial interest in the PoST network’s success by allocating some form of memory or hard-disk drive space towards it. The proof can then be used to achieve decentralized consensus in a blockchain network or other decentralized protocol. Proof of financial interest in the network is crucial to a decentralized system’s success as it defends the system against Sybil attacks.
The key difference between PoST and PoW is that in the former, storage capacity indicates financial investment in the network instead of computing power and the associated electricity consumption cost which PoW entails. As a result, PoST has the potential to be far less impactful on the environment than PoW, i.e., greener.
Popular cryptocurrency projects that utilize PoST consensus systems are Filecoin, Chia Network, and Spacemesh. Chaingreen is the latest addition to the green cryptocurrency group. The project’s goal is to become an eco-friendly alternative to Bitcoin, allowing participants to harness the power of their hard-disk drives and start farming immediately. Find out more about Chaingreen in this blog post.