ReactJS, a JavaScript-based library developed by Facebook, revolutionizes front-end development by enabling the creation of dynamic user interfaces through reusable components and a virtual DOM. It offers features such as JSX syntax, one-way data binding, and enhanced rendering speed, making it ideal for developing scalable and efficient single-page applications. Employing ReactJS allows developers to write cleaner code, reduces loading times, and improves SEO friendliness, ultimately facilitating modern web and mobile app development.