React is a JavaScript library for building reactive UIs. We usually use jQuery or pure JavaScript to manipulate a reactive UI whenever the application state changes, which makes it difficult to reuse and understand the code. Instead, we can use React, which lets us declare how the UI behaves based on the application state, and it automatically updates the UI whenever the application state changes. There are lots of libraries and technologies, such as web components and templating engines, that aim to make the building of UIs easier, but React stands out from the crowd as it makes it easy to build reusable and high-performance reactive UIs.
React is also used as a view library because it is exactly what a view library is supposed to be. A view holds the UI of the application and defines how the UI changes based on the application state, that is, how the application state is displayed. As it's just a view library, it doesn't tell us how to manage, access, and mutate the application...