What is the difference between state and props in React?

Great question! Understanding the difference between **state** and **props** in React is fundamental to managing data flow and component behavior effectively. ### What are Props? **Props** (short for "properties") are inputs to a React component. They are passed down from a parent component to a child component and are **read-only** inside the child. This means a component receiving props should not modify them — props are meant to provide data or configuration from the outside. For example, if you have a `` component, a parent might pass the user's name as a prop: ```jsx ``` Here, `name` is a prop inside `UserProfile`. The component can **use** this data to render UI but should not change it. ### What is State? **State**, on the other hand, is data that is **managed within the component itself**. State is mutable, meaning a component can update its own state over time, typically in response to user interactions, network responses, or other internal events. For example, a `` component might have a `count` state that changes when the user clicks a button: ```jsx const [count, setCount] = useState(0); ``` Here, `count` is state internal to the component, and calling `setCount` updates it, causing the component to re-render with the new value. ### When Should Data Live in State vs. Props? - **Use props when:** - The data is **owned and managed by a parent** component. - You want to **pass data down** to child components without allowing them to change it. - The child component is a "presentational" or "stateless" component that just renders based on input. - **Use state when:** - The data is **owned and managed by the component itself**. - The data changes over time due to user actions, timers, or other events. - You need to keep track of UI details like form inputs, toggle switches, or fetched data that the component updates internally. ### Summary - **Props:** Read-only, passed from parent to child, used for configuring or displaying external data. - **State:** Mutable, owned and updated by the component itself, used for dynamic data that changes over time. In practice, data often flows **down** via props, and events or callbacks flow **up** to notify parents of changes, which may then update state and pass new props down again. This promotes a clear, predictable data flow in your React apps. I hope this clarifies the difference! Let me know if you'd like examples or further details.