Function modifiers are components used in smart contracts, particularly in programming languages like Solidity, to enhance or change the behavior of functions. They allow developers to impose specific conditions or rules before the execution of a function.For example, a modifier can ensure that only the contract owner can execute a certain function. When a function is prefixed with a modifier, the conditions defined in that modifier are executed first. If those conditions are met, the rest of the function proceeds; if not, execution halts.Modifiers contribute to security and efficiency, helping prevent unauthorized access or undesirable states. They streamline code by allowing developers to reuse the same condition across multiple functions without rewriting the logic.Common use cases for function modifiers include access control, validating inputs, and managing state changes. By implementing modifiers, developers can create clearer, more maintainable contracts while ensuring that critical rules are consistently enforced.