Bootstrap 3
Bootstrap 3, formerly known as Twitter's Bootstrap, is a CSS and JavaScript framework for building application frontends. The three in Bootstrap 3 refers to the third version of this framework; wherever Bootstrap is written in this book, it refers to this third version. The third version of Bootstrap has important changes over the earlier versions of the framework. Bootstrap 3 is not compatible with the earlier versions.
Bootstrap 3 can be used to build great frontends. You can download the complete framework, including CSS and JavaScript, and start using it right away. Bootstrap also has a grid. The grid of Bootstrap is mobile-first by default and has 12 columns. In fact, Bootstrap defines four grids: the extra-small grid up to 768 pixels (mobile phones), the small grid between 768 and 992 pixels (tablets), the medium grid between 992 and 1200 pixels (desktop), and finally, the large grid of 1200 pixels and above for large desktops . In Chapter 5, Integrate Less in Your Own...
