Bootstrap is a front-end java script framework containing tools for creating and designing websites and web application as well.It includes CSS templates for typography, buttons, forms, interface components some java script extensions and HTML . It provide facilties to makes dynamic websites
Bootstrap supports CSS framework due to which web development improves too much.
Bootstrap have a 12 column built-in grid(This grid is known as fluid grid which is control by media queries).By the use of grid we can make our website/web application responsive.Responsiveness is actually the behavior of our website/web application on different devices like desktop, mobile phone and tablets.Defiantly the websites made for desktop can never show same behaviour on mobile phone screen or of tablet ,so to minimized this problem we can now make our websites responsive. So by the responsive design layout is arranged in the way that all the important information is presented in any kind of device or screen.
BUILT-IN CSS COMPONENTS:
Bootstrap have some of the java script components in the form of jQuery plugins.These components provides extra user interface elements like dialogue boxes, tooltips and carousels