Invariant check refers to a mechanism used to ensure consistency and correctness of data within a blockchain or smart contract. It verifies that certain predefined conditions and invariants hold true throughout the operation of the system.For example, in a decentralized finance (DeFi) protocol, invariant checks might ensure that the total supply of tokens remains constant during trades or that the sum of asset values in a liquidity pool matches the values distributed among participants. This prevents errors like duplicate transactions or balance discrepancies.Implementing invariant checks is crucial for maintaining trust and security, as they help catch potential mistakes or vulnerabilities before transactions are finalized. Automated checks are usually performed during the execution of transactions to ensure compliance with the rules encoded in the smart contract.By verifying the invariants, developers can prevent exploits and ensure that the platform behaves as expected, thereby safeguarding user funds and promoting confidence in the system.