React.js and Next.js are two popular JavaScript frameworks used for developing web applications.

React.js is a JavaScript library that is used for building user interfaces. It was developed by Facebook and is now maintained by a community of developers. React.js is popular because it allows developers to create reusable UI components that can be used across an entire application.

Next.js is a framework built on top of React.js that adds several features to simplify the process of building server-rendered React applications. It was developed by Vercel and is open-source. Some of the features of Next.js include server-side rendering, automatic code splitting, and optimized performance.

As of March 2023, the latest version of React.js is version 18.0.0, which was released in November 2021. The latest version of Next.js is version 13, which was released in February 2023. This latest release includes improvements to performance, accessibility, and developer experience, among other features.

Overall, React.js and Next.js are both powerful tools for building web applications, and choosing between them will depend on the specific needs of your project. React.js is a great choice if you need to build reusable UI components, while Next.js is a good option if you need server-side rendering and other performance optimizations.