what does bootstrap do code example

Example 1: what is bootstrap

Bootstrap is a free and open-source CSS framework directed at responsive,
mobile-first front-end web development developed by TWITTER

It contains CSS- and JavaScript-based design templates for typography, forms,
buttons, navigation, and other interface components.

Example 2: what is bootstrap

# Bootstrap is the most popular HTML, CSS and JavaScript framework for 
  developing a responsive and mobile friendly website.
# It is absolutely free to download and use.
# It is a front-end framework used for easier and faster web development.
# It includes HTML and CSS based design templates for typography, forms, 
  buttons, tables, navigation, modals, image carousels and many others.
# It can also use JavaScript plug-ins.
# It facilitates you to create responsive designs.

Bootstrap was developed by Mark Otto and Jacob Thornton at Twitter.It was 
released as an open source product in August 2011 on GitHub.
In June 2014 Bootstrap was the No.1 project on GitHub.

Example 3: bootstrap js

<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css" integrity="sha384-Gn5384xqQ1aoWXA+058RXPxPg6fy4IWvTNh0E263XmFcJlSAwiGgFAW/dAiS6JXm" crossorigin="anonymous">