bootstrap is a html – css framework mainly used for making responsive websites. Bootstrap have some predefined classes, using those classes we can make the website responsive
to all device easily, no need to write separate styles for small devices.
Newest version of bootstrap is bootstrap 4. contains some more classes.
Main properties of bootstrap websites are: responsive, compatible in all browsers, minimal code in our own html and css files.
bootstrap can be included in our website template in two ways.
Either download stylesheet and jquery from https://getbootstrap.com . Here we can also download customized bootstrap files for our website(outer width, container width, grid gap etc).
or we can use CDN links to include all files for bootstrap.