By Håkon Wium Lie and Bert Bos
What is CSS?
CSS stands for Cascading Style Sheets and is a simple styling language which allows attaching style to HTML elements. Every element type as well as every occurance of a specific element within that type can be declared an unique style, e.g. margins, positioning, color or size.
What are Style Sheets?
Style Sheets are templates, very similar to templates in desktop publishing applications, containing a collection of rules declared to various selectors (elements).
What is external Style Sheet? How to link?
External Style Sheet is a template/document/file containing style information which can be linked with any number of HTML documents. This is a very convenient way of formatting the entire site as well as restyling it by editing just one file.
The file is linked with HTML documents via the LINK element inside the HEAD element. Files containing style information must have extension .css, e.g. style.css.