How i can separate links for (Bootstrap, jQuery, CSS, JS) in separate file and attach link of that file in HTML page

i am making a simple website using (html,css,bootstrap,javascript,jquery).My question’s are

1. How I separate all links or scripts tag in a separate file and then include this file in my index.html

2. how i can make bootstrap globally accessible to all my project files.

because without it. My head tag is messed up and I want to write clean code

I’m sure there’s a way to do it, but the general convention is to add all script tags in your HTML file. Now, your head tag does not need to be bloated as it is better to place your script tags at the end of body. Scripts block additional resources from being downloaded more quickly so by placing them at the bottom, your style, content, and media can download more quickly. In most HTML files today you’ll see script tags at the bottom, just before </body>.