"Props" is short for properties. They are a fundamental concept in React for passing data from parent components to child components. Think of props as arguments you pass to a function (your component).

Props are read-only from the perspective of the child component. This means a child component should never modify the props it receives directly. This principle helps enforce a unidirectional data flow, which makes your application easier to understand and debug.

How to Use Props:

// Parent Component
function App() {
return <Greeting name="Alice" />;
}

// Child Component (Function Component)
function Greeting(props) { // props is an object: { name: "Alice" }
return <h1>Hello, {props.name}!</h1>;
}

// Child Component (Class Component)
class GreetingClass extends React.Component {
render() { // Access props via this.props
  return <h1>Hello, {this.props.name}!</h1>;
}
}

You can pass any JavaScript value as a prop, including strings, numbers, booleans, arrays, objects, and even functions (which is how child components can communicate back to parent components).