Selfish Mining

Selfish Mining, also known as a ‘block withholding attack,’ is an economic attack vector in blockchain systems. In this attack, a mining pool delays the release of a discovered block(s) to attempt to secretly mine further blocks while the rest of the network wastes energy mining what will become an orphan block. The attack is possible partly because Nakamoto Consensus describes the valid chain as identified by its length (or, more appropriately, total work) rather than first-seen basis, so the selfish mining pool could theoretically publish a longer chain after other miners discover the initial block.