You can create a stand alone set of instructions a Style Sheet - to which you then link as many pages of your site as you wish. This single style sheet will control the appearance of all the pages. This is a term that seems to cause an immense amount of confusion. The basic thing to remember is that you can use each of the three different types of style sheet, as defined above, in the same web site. Where neither an inline not an embedded style is used the linked style will apply This is referred to as the cascade .
Lets look at it another way.
Suppose you have a web site that includes a style sheet to which all pages are linked, giving it a nice professional and consistent appearance. But you have a single page that you want to appear radically different from the others. You can simply place an embedded style sheet in the head of this page and that style sheet will override the linked one on that page. Now you look at this page and it is fine except for one small section that, again, you would like to appear in a different format. Simply apply an inline style and this will, in turn, over ride the embedded one.