Frontend and Backend Frameworks

React organizes an interface into components — self-contained, reusable pieces of UI, typically written as functions that return a description of what should appear on screen. Components receive data from their parent through props (short for properties), which are read-only and flow in a single direction down the component tree, and they manage their own internal, changeable data through state, most commonly via the useState hook in modern React. When state changes, React re-renders the affected component and its children, recomputing what the UI should look like from scratch conceptually, even though the actual DOM update is far more selective in practice. This one-directional data flow, sometimes summarized as "props down, events up," is central to React's mental model: a child component cannot directly modify a prop it receives, but it can call a function passed down from its parent to request a change, keeping data flow predictable even in large applications.