Bootstrap 4 is the latest version of Bootstrap which is the world’s most popular HTML, CSS, and JavaScript framework for the development of Responsive, mobile-first projects on the web. It is an open-source toolkit for developing HTML, CSS, and JS. Bootstrap 4 comes with new components, faster stylesheet, and more responsiveness. It is a free front-end component library for faster and easier web development. Bootstrap 4 supports all major, modern browsers and platforms. It is compatible with desktops, phones as well as tablets.