What's the Difference Between assert and require in Solidity?

In Solidity, assert and require are used for handling errors and exception conditions, but their purposes and behaviors have significant differences:

• require: Typically used for input validation or ensuring conditions are met prior to contract execution. If require's condition fails, the transaction is reverted, all state modifications are rolled back, and the remaining gas is refunded. require is well-suited for checking external conditions (such as function parameter values or contract state).

• assert: Used for checking internal errors that should not occur during code execution. Typically, assert is employed to detect errors or inconsistencies in the contract's internal state. If assert's condition fails, the transaction is reverted and all state modifications are rolled back. However, unlike require, assert failure consumes all provided gas.

In short, require is used for input or condition checks, while assert is used to ensure the correctness of code logic during execution.