How to Attach a CSS Stylesheet to an HTML Document
Linking a CSS file to an HTML file allows you update the styling of the HTML document by editing the CSS file. This is especially useful if, for example, you have hundreds of pages that you'd like to style from one central location. Using CSS, you can completely customize the look and feel of your website at once.
This is part of our series on using CSS in HTML, it includes other guides like this one on how to open the telephone app using an HTML link.