Of all css frameworks, bootstrap is best known. It is a free and open-source mobile first css framework that include HTML and CSS design templates for common user components like Typography, Forms, Buttons, Tables, Navigations, Dropdowns, Alerts, Modals, Tabs, Accordion, Carousel and many other component as well as optional JavaScript extensions. According to wikipedia Bootstrap is the second most-starred project on GitHub. Bootstrap was developed by Mark Otto and Jacob Thornton and originally was named Twitter Blueprint and first release was on August 19, 2011. Today we are mostly using bootstrap 3 but there is also bootstrap 4 alpha version.

The advantage of using bootstrap is that save you lots of time, you get responsive features form start, consistent design, easy to use. Besides that it's compatible with all browsers, therefore you don't have to worry about it. Bootstrap is best known for its grid, which is one of the most essential features of the frameworks. It have 12 columns across the page that you can use, You can use all 12 columns individually or you can group it together to create wider columns.

It's very easy to use bootstrap, it already have starter template that you can use.

 Unlike many web frameworks, it concerns itself with front-end development only. Ther are two version for now. Stable version 3.3.7 and preview version v4.0.0-alpha.6.