What is Bootstrap?
Bootstrap is a free and open-source tool collection for creating responsive websites and web applications. It is the most popular HTML, CSS, and JavaScript framework for developing responsive, mobile-first websites. Bootstrap contains the basic tools and elements you will need in most of your projects such as: tables, buttons, text and form tools, heading, navigation, backgrounds, and more. Bootstrap saves designers a lot of time and effort while designing pages. All they need to know is the class names they will work with to give the appropriate formatting to their element. In addition, the Bootstrap framework makes the design fit and responsive to all different screen sizes and browsers.
Bootstrap was conceived by Mark Otto and Jacob Thornton, who were working at Twitter in 2010. The project was released in 2011 as open source. Since then Bootstrap has become a highly popular framework due to its ease of use and ability to deliver cross-platform compatibility between many browsers and devices.