Bootstrap is becoming a popular web layout system for the web. It was started by a designer/developer who worked at Twitter in 2010, and currently is at version 3.1.1.
Bootstrap is a web framework. This means that it has identified common problems that web designer and developers run into, and tries to provide easy solutions to them. This is much like jQuery UI and jQuery Mobile, or the 960 Grid System.
Bootstrap does actually need the base jQuery library to work.
The layout solution for Bootstrap is responsive in nature, so it will change sizes based upon the size of the display screen. If you drag one corner of your browser’s window to resize it, you can see the sections change as you resize it.