What is bootstrap and how to use it?

Bootstrap is a free and open-source front-end framework for designing websites and web application.

In my opinion:

Mark Otto and Jacob Thornton from twitter developed css and javascript files such a way that we (web-designers) don’t need to spend hours to think about the responsive framework and design. Besides it is free and open source so we can use bootstrap to develop websites and web applications for clients so easily like never before. You only need to remember the css classes when designing a responsive website or application. If you want to make any change in the design or property then you have to modify the property in the css or js file. The very new front-end web designers manly work with HTML, CSS, Javascript with very little knowledge and experience. But once they start using bootstrap then they can easily design beautiful websites without having deep knowledge in css and javascript in no time. The new designers will get some basic frameworks to start with from https://getbootstrap.com

Then from examples choose any theme then press CTRL+U and you will get the sample code of the theme.

You can use bootstrap in two ways in your website. First, You download the latest version of bootstrap codes from https://getbootstrap.com or you can put the links in the head section into your website. That you will get from the bootstrap official website under BootstrapCDN.

<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.1.2/css/bootstrap.min.css" integrity="sha384-Smlep5jCw/wG7hdkwQ/Z5nLIefveQRIY9nfy6xoR1uRYBtpZgI6339F5dgvm/e9B" crossorigin="anonymous">
<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.1.2/js/bootstrap.min.js" integrity="sha384-o+RDsa0aLu++PJvFqy8fFScvbHFLtbvScb8AjopnFD+iEQ7wo/CG0xlczd+2O/em" crossorigin="anonymous"></script>
<script src="https://code.jquery.com/jquery-3.3.1.slim.min.js" integrity="sha384-q8i/X+965DzO0rT7abK41JStQIAqVgRVzpbzo5smXKp4YfRvH+8abtTE1Pi6jizo" crossorigin="anonymous"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.3/umd/popper.min.js" integrity="sha384-ZMP7rVo3mIykV+2+9J3UJ46jBk0WLaUAdn689aCwoqbBJiSnjAK/l8WvCWPIPm49" crossorigin="anonymous"></script>