React.js and Node.js are both JavaScript technologies used for web development, but they have different purposes: React.js A front-end library that creates user interfaces (UIs) for web applications. React.js is known for its declarative approach to UI development, and it's often used for single-page applications and mobile apps. Node.js A runtime environment that runs JavaScript on the server side of an application. Node.js is often used for building APIs, real-time web applications, and other server-side applications. React.js and Node.js are often used together in full-stack JavaScript applications to handle both server and client-side tasks. For example, Node.js can run the web server for hosting a React application. Here are some more details about React.js and Node.js: React.js React.js uses reusable UI components that can be updated efficiently when data changes. It's well-suited for applications with many components, such as user login, access rights, and statuses that change often. Node.js Node.js is built on Chrome's V8 JavaScript engine, which compiles JavaScript into machine code. It's event-driven, nonblocking, and asynchronous, which makes it good for building real-time web applications. Node.js can also handle data streaming, file uploads, and broadcasting media.