Bootstrap is a free and open source front end framework that makes it easier to code beautiful, fully responsive, and heavily interactive websites and web applications.
Bootstrap was created in mid-2010 by a designer and developer working at Twitter, and ince then Bootstrap has grown to be the most commonly used CSS framework and second most commonly used JavaScript library on the web. According to W3Techs, 18.9% of all websites in the world use Bootstrap, among them brand name companies like Microsoft, Udemy, Spotify, and UpWork.