Event handling in [React](/courses/reactjs) lets components respond to user interactions such as clicks, typing, form submission, keyboard input, focus, and mouse movement. You handle an event by passing a [function](/javascript/functions-in-javascript) to an event prop such as `onClick`, `onChange`, or `onSubmit`. ### Basic Click Event ```jsx function SaveButton() { function handleClick() { console.log("Saved"); } return ( ); } ``` The flow is: ```text User clicks button ↓ React receives click event ↓ handleClick runs ↓ application performs action ``` ### Event Handler Naming A common convention is: ```text onClick → handleClick onChange → handleChange onSubmit → handleSubmit onMouseEnter → handleMouseEnter ``` The names are conventions rather than special [React](/courses/reactjs) requirements. ### Inline Event Handlers For small logic, you can write the handler directly: ```jsx ``` For longer logic, a named [function](/javascript/functions-in-javascript) is usually easier to read: ```jsx function handleDelete() { // validation // update state // call API } ``` ### Event Handlers Can Update State ```jsx function Counter() { const [count, setCount] = useState(0); function handleClick() { setCount((count) => count + 1); } return ( ); } ``` Unlike rendering code, event handlers are appropriate places for actions caused by user interaction, such as updating state or starting a request. ### Passing Event Handlers to Custom Components A parent can also provide behavior to a reusable component: ```jsx function Button({ onClick, children }) { return ( ); } function App() { function handleSave() { console.log("Saving..."); } return ( ); } ``` This separates reusable UI from the action that should happen when it is used. ### Interview-Ready Answer React handles user interactions by passing event-handler functions to JSX props such as `onClick`, `onChange`, and `onSubmit`. React calls the supplied function when the event occurs. Event handlers can read event information, update state, call other functions, and be passed between components as props.