What is the difference between state and props in React.js?

In React.js, both state and props are important concepts that facilitate the management and flow of data within components, but they serve different purposes:

1. State:

   • State is a JavaScript object that represents the current condition of a component. It holds data that might change over time.
   • State is managed internally by the component itself and can be modified using the setState() method provided by React.
   • Changes to the state trigger re-rendering of the component, allowing the UI to update to reflect the new state.
   • State is initialized within the constructor of a component using this.state = { /* initial state */ };, and it can be updated using this.setState().

2. Props:

   • Props (short for properties) are inputs to a React component. They are passed from parent components down to their children as read-only attributes.
   • Props allow parent components to pass data to their children components. They are immutable, meaning that child components cannot modify the props received from their parent.
   • Changes in props passed by a parent component automatically trigger a re-render of the child component receiving the updated props.
   • Props are specified as attributes on custom components when they are used within other components.

Feature	State	Props
Definition	Internal data specific to a component	External data passed to a component
Mutability	Can be updated and changed	Immutable and read-only
Initialization	Defined within the component	Passed from parent component
Access	Accessed using this.state	Accessed using this.props
Modification	Updated using setState() method	Cannot be modified within a component
Scope	Local to the component	Received from parent component
Trigger Re-render	Changes in state trigger re-render	Changes in props trigger re-render
Ownership	Owned and managed by the component	Controlled by parent component

In summary, while state is internal to a component and can be modified by the component itself, props are passed down from parent to child components and remain immutable within the child components. Both state and props are integral parts of React's data management system and help in building dynamic and interactive UIs.