Next.js is a React framework that gives you building blocks to create web applications. Next. js works very similarly to React, only with some very useful tools that don't come out of the box in React. By framework, we mean Next.js handles the tooling and configuration needed for React, and provides additional structure, features, and optimizations for your application.
Next. js solves the SEO problem by server-side rendering pages so Google can index them appropriately. It also provides a way to build isomorphic apps using the same codebase for client-side routing and server-side rendering. This means that each page exists before being rendered by the browser client-side. In other terms, any web crawler can index them all effortlessly and treat them differently based on their content. So, Next. js is inherently an excellent tool to achieve great SEO performance.
It's easy to code - compared to React itself and other frameworks working with React, Next. js requires less code. Developers just have to create the page and link to the component in the header, which means less code, better readability, and improved project management. Speed - Applications built with Next.
If you're planning on creating a web application with server-side rendering; If you already have the knowledge about React, but you're looking for more functionalities; Whenever you plan on building a static site; Lastly, if you want to build an MVP and reduce time-to-market, Next JS should be your go-to framework.
You don't need to master React, but you should have at least some React knowledge as they are both built upon React, and the flow of the work is hugely based upon the React way of doing things. Definitely go through the official React tutorial if nothing else before learning Gatsby or Next.