In the previous example, we defined styles by describing them in the <head></head> section of our document. This is quite convenient, but what if we have to work with a large number of pages on the site?
It is very simple to define styles in a separate file, which can be “connected” to all pages of the site.The style file must have an extension .css (typically, this file is called styles.css).
The <link> tag should be placed in the <head></head> section of all pages of the site where you want to use the styles described.css styles.
The advantages of using an external CSS file are quite obvious there is no need to edit the styles on each page of the site, it is enough to make changes to the styles only once.css, and its action will extend to all the documents to which it is connected.