Inline Style Declaration: In Transitional HTML, Style rules can be included directly into the text, using the Style attribute. However this approach is deprecated in Strict HTML and can be time-consuming to maintain.
Embedded Style Declaration: Style rules can also be incorporated into the <Head> element using selectors to affect the entire document. While this allows Style rules to be consistent throughout the document, it can still be time-consuming to keep Styles consistent between many documents in a single site.
External Style Sheet: The most convenient way to maintain consistent Style throughout the site is to put all the style rules into an external file and <Link> to it in the <Head> element. The external style can still be overridden by either of the above methods.