Bootstrap is a front end frame work created by a developer and designer at twitter. front end refers to the client side of the website, that’s the practical website displayed in the browser window.A frame work is a bunch of code written for you already,which you can use to build your website ,You can find twitter bootstrap at getbootstrap.com
Pre written code that's look like a terrible idea.
A site looks with bootstrap is immediately recognizable like the default templates word press,joomla and drupul templates .Bootstrap supports both adoptive layout and responsive design,depending on which type of grid you choose.you can also pull out responsive elements and build standard website. If you are not a designer you love the elements of the websites designed for you cleanly and simple so you can make a reasonable website making quickly without worrying about all of the design detail.
Designers will love how easily they able to overwrite colors and styles in bootstrap,So you can leverage layouts in java script effects.But tweet the css by the ways exactly the way you want. Bootstrap comes with java-script,css and some image files that you can visit on your website. a 12 coloum grid system is available,as well as multiple navigation systems including drop-downs tabs.and buttons as well as cool java-script effects like model windows and image carousal and much more .You can find examples of websites build with bootstrap at http://builtwithbootstrap.com/