Under the hood of React JS, as mentioned earlier, is JavaScript scripting language. It is a text-based language that makes web applications interactive. Compared to other programming languages such as HTML or CSS, which are responsible for static elements like the structure of a web app, JavaScript is responsible for clickable elements that occupy the user. That's why React is an excellent solution for dynamic web applications. React API (Application programming interface) is relatively small, making its use more intuitive and straightforward than other technologies. To be more precise, to create user interfaces, React operates on two main APIs - React vDOM and React component API. The previously mentioned React components, which are responsible for building the UI quickly and efficiently, like using Lego blocks, use JSX (JavaScript XML). React vDOM stands for quicker refreshing of pages and better stability.