It is a derivative of the Proof-of-Stake consensus mechanism. The first blockchain to process and use Pure Proof-of-Stake is Algorand. In order to participate in block validation it is sufficient to have 1 ALGO in staking. The entry requirements are therefore very low and in this way many people can participate, any user of the Algorand network can be selected as a validator randomly and anonymously. The selection is done by means of the VRF (verifiable random function) developed by founder Silvio Micali, which randomly chooses validators but taking into account their stake size. In fact in Pure Proof-of-Stake the probability of being chosen is open to all but is directly proportional to the size of the stake. When a node is selected, nobody but them knows about it. Anonymity preserves from corruption, since if nobody knows the identity of the selected block, nobody can try to compromise it.
Validating a block requires several steps and the combined work of several users. Initially a validation leader is selected out of all the ALGO owners, to propose the addition of the block; then the block is passed under the control of a committee of randomly selected users. The committee ensures that there are no problems with the transactions contained in the block (e.g. double spending). A second committee is appointed to confirm the block. If there are problems with a block, it is discarded and a new leader is elected. In Pure Proof-of-Stake there are no punishment mechanisms for blocks that do not do their job properly, in these cases the network discards the validator and starts working again without interruption. Pure Proof-of-Stake does not involve slashing but focuses on fast processing of transactions by resolving errors quickly.