External CSS Style Sheet
When used as an external page the use of single CSS style sheet for page layout and design allows you to change the layout or display of an element or page by making a single change on one page and have that change take affect or Cascade throughout the site. Doesn't matter if you have a 10 page website or 10,000 page website.
An external style sheet is linked to an HTML document through HTML's link element:
<link rel="stylesheet" type="text/css" href="style.css"
media="screen" />
The <Link> tag is placed in the document head.
The rel attribute is used to define the relationship between the linked file and the HTML document. rel="stylesheet" specifies a persistent or preferred style
The type attribute is used to specify the document type. Configuring the server to send text/css as the Content-type.
The href attribute tells the browser where to find the style sheet
The <LINK> tag also holds an optional Media attribute, which specifies the medium or media to which the style sheet should be applied.. This allows browsers to ignore style sheet types that they do not support.
External style sheets do not contain any HTML tags like <HEAD> or <STYLE>.
The style sheet must consist merely of style rules or comment statements.p {line-height:1.5em;}
/* This is a comment */