Bootstrap files linking in html file

Hi  I'm new to WebStorm and wanted to start bootstrap project but I'm little confused

is that necessary (like vscode)  to link bootstrap.js and bootstrap.css to my html file

because ide intellisense is showing me Bootstrap class names without linking these files in my html 

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The IDE shows you the existing classes in completion, this is expected. But you still need linking the files in order to run your code, CSS classes won't be available when you open your app in browser unless you link them to your page