Understanding React: A Library and a Rendering Framework

React is a library because developers explicitly call the method provided by the library. At the same time it is a rendering framework because the developer does not explicitly write any code to render. React decides when to render and what to render, and where it needs to render something.

React is often referred to as a library because it provides a set of functions (like useState, useEffect, useRef, and many others) and classes (like Component) that you can use in your application. These functions and classes are like tools in a toolbox, and you, the developer, get to decide when, where, and how to use them.

On the other hand, React can also be seen as a framework because of the way it handles rendering. Unlike libraries, which generally require the developer to explicitly call their functions when needed, React automatically re-renders components whenever their state or props change. You don’t need to manually update the DOM whenever your data changes, React will handle this for you. This is more in line with the way frameworks operate, where they provide a predefined structure and handle certain things automatically.

So while React is officially classified as a library, in practice it blurs the line between a library and a framework, possessing characteristics of both.