In programming, which term describes a line of code that allows a language to respond to a specific event or user input?

The term that describes a line of code that allows a programming language to respond to a specific event or user input is "event handler." An event handler is a piece of code specifically designed to execute in response to a particular event, such as a user clicking a button, submitting a form, or moving the mouse. This mechanism is crucial in interactive programming, particularly in web development, where clients expect immediate feedback and actions based on their inputs.

Event handlers work by listening for specified events that occur within the browser or application environment; when the designated event occurs, the associated handler is invoked, leading to the execution of the code that responds to the event. This dynamic interaction forms the backbone of user engagement in applications and significantly enhances the user experience.

The other terms, while related to programming, do not specifically describe the mechanism that responds to events. A function generally represents a reusable block of code that performs a specific task but does not encompass the event-driven aspect of handling user inputs directly. A callback refers to a function that is passed as an argument to another function and is executed after the completion of that function, rather than being directly tied to an event. A procedure is a series of programmed statements that perform a task, often used interchangeably with functions,