An Event Listener is a programming construct that waits for specific actions or events to occur in a software application. When an event, such as a mouse click or a key press, happens, the event listener responds by executing a predefined function or block of code. This allows developers to create interactive and dynamic user experiences in applications. In web development, event listeners are commonly used with elements like buttons, forms, and links. They are often implemented using languages like JavaScript, enabling developers to enhance user interfaces by responding to user actions in real-time.