A type of proof of stake cryptocurrency protocol used in Ethereum mining is referred to as Casper. When transaction records are recorded on the blockchain, miners are entrusted in performing these activities so as to ensure that actual data are recorded appropriately. But there are problems associated with adding blocks to the blockchain since transactions recorded by miners come with rewards and this is referred to as Byzantine Generals Problems.
Casper was designed to address the issues with ethereum proof of stake protocol by punishing validators who fail play by the rules. It does this by reducing nodes to increase network security for validators using nothing at stake strategy and those who go offline non intentionally or even intentionally.