React Technologies

React JS
React JS is a JavaScript library for building user interfaces, primarily for web applications. It was developed by Facebook and is now maintained by Facebook and a community of individual developers and companies. 

Key features of React JS include:

• Component-Based Architecture: React applications are built using components, which are self-contained modules that encapsulate both the structure (HTML), behavior (JavaScript), and sometimes style (CSS).
• Virtual DOM: React uses a virtual DOM to improve performance. Instead of directly manipulating the browser's DOM, React creates a virtual copy and updates the browser's DOM in a more efficient manner.
• Declarative Syntax: React allows developers to describe what the UI should look like. When the data changes, React efficiently updates and re-renders the appropriate components.
• JSX: React uses JSX, a syntax extension that allows HTML to be written within JavaScript. JSX makes it easier to write and visualize the structure of UI components.

React Native
React Native is a framework for building native mobile applications using JavaScript and React. It allows developers to write code that runs on both iOS and Android platforms with a single codebase. 

Key features of React Native include:

• Native Components: React Native provides components that wrap native code, giving the app a native look and feel.
• Single Codebase: Developers can write code once and run it on multiple platforms, reducing development time and effort.
• Hot Reloading: This feature allows developers to instantly see the results of the latest change without rebuilding the entire app.
• Performance: Since React Native uses native components and modules, it offers better performance compared to hybrid apps that rely on WebView.

React VR
React VR is a framework for creating virtual reality applications using React. It leverages the same concepts and tools as React and React Native but is tailored for VR experiences. It was later evolved into React 360. 

Key features React VR include:

• 3D and VR Environment: React VR allows developers to create 3D user interfaces and VR experiences.
• WebGL and WebVR: React VR uses WebGL for rendering 3D graphics and WebVR for VR headset support.
• Declarative Components: Similar to React JS and React Native, React VR uses a component-based approach, making it easier to build complex VR applications.

React Fiber
React Fiber is the new reconciliation algorithm in React. It is a complete rewrite of the old reconciliation algorithm. The primary goals of React Fiber are to enable incremental rendering of the virtual DOM and improve the responsiveness of applications. 

Key features React Fiber include:

• Incremental Rendering: React Fiber allows rendering work to be split into chunks and spread out over multiple frames. This helps in rendering large lists or complex views without blocking the main thread.
• Better Performance: Fiber improves the efficiency of rendering updates, reducing the time it takes to render complex UIs.
• Improved Layout: It includes better handling of layout changes, animations, and gestures.
• Concurrency: React Fiber introduces concepts of "time slicing" and "priority levels," enabling React to work on higher-priority updates without blocking lower-priority ones.

Summary

1. React JS: A JavaScript library for building web user interfaces using a component-based architecture and a virtual DOM.
2. React Native: A framework for building native mobile apps using React, with shared codebase for iOS and Android.
3. React VR (React 360): A framework for creating VR applications using React concepts, tailored for 3D and VR experiences.
4. React Fiber: A new reconciliation algorithm in React aimed at improving performance and responsiveness through incremental rendering and better handling of updates.

Each of these technologies builds upon the foundational principles of React, extending its capabilities to different platforms and enhancing its performance and usability.