A JavaScript syntax extension that lets you write markup-like code inside JavaScript and compiles to React.createElement calls.

Reusable UI pieces that describe what should appear on screen and can manage their own state or rely on props.

Immutable inputs to a component passed from its parent.

Data managed within a component that can change over time and triggers re-renders when updated.

A special function starting with 'use' that lets functional components use state and other React features.

It handles side effects such as data fetching, subscriptions, or DOM manipulation after render.

It declares a state variable within a functional component and provides a setter to update it.

React 18 added concurrent rendering and automatic batching; React 19 introduces Server Components, the new compiler, and use() for async data.

React 19’s components that run on the server to fetch data and stream rendered HTML to the client efficiently.

Declarative async loading boundaries that allow React to pause rendering parts of the UI while data or code loads.

It enables optimistic UI updates — updating UI immediately before a server mutation resolves or fails.

useContext shares state globally; useReducer manages complex local state transitions. Often combined for global state patterns.

An API that allows server-side form actions and optimistic updates using async functions in form ‘action’ attributes.

React can interrupt and resume rendering work, making UI more responsive and allowing features like Suspense and transitions.