About Twitter Bootstrap

Mark Otto and @fat are the cofounders of twitter bootstrap who had also done a good job on describing it, in short lines:

Bootstrap is a very simple way to promote quick, clean and highly usable applications , providing a clean and uniform solution to the most common, everyday interface tasks developers come across.

Twitter bootstrap is a new form of development toolkit designed to make your life easier. It enables its users to create web apps and websites now faster than ever. It also includes all possible components any type of site needs: base css, javascript, work for smaller resolution devices, wells, utilities, animations, navbars, progress bars, thumbnails, etc. Everything you could ever ask for is right here in one place.

You can tell the potential of this toolkit just by the fact that even NASA uses it, and you can check their projects here
http://code.nasa.gov/project/

Since bootstrap is a rather new piece of toolkit, it is made to support all kinds of newer web browsers especially the popular ones such as Google Chrome, Mozilla Firefox, Opera, Safari and similar. So you never have to worry that your site will be outdated in that matter!