IOST verifies transaction by applying “Proof-of-Believability” (PoB) . This is a form of staking with two groups. This separates all of the IOS nodes into two leagues: believable and normal. First, nodes from the believable league quickly process transactions. After that, the normal nodes validate samples of the transactions and provide verifiability.
The likelihood of a node being selected for the believable league is based on its believability score. This score is comprised of the token balance, reviews, and community contributions, among other things.
The purpose of the normal nodes is to ensure that the believable nodes are acting honestly. If a normal node catches a believable node acting dishonestly, that believable node will lose all of its tokens and its believability score will return to zero.