Cascading style sheets (CSS)

Is a data format which is used to separate style from structure on a Web page. CSS addresses many of the trials and tribulations of the old style HTML. The older tags such as , muddle Web page source code and make for rigid web sites. With CSS, style information can be centralized. This centralization leads to increased power and flexibility. CSS’s most common use as an application is to style web pages written in HTML and XHTML.

With CSS, designers are able to use tags to reference a certain style rather than having to describe it at each occurrence. Therefore when a style needs to be changed, only the referenced declarations would need to be changed, and not all of the occasions where it has been used.

CSS information can be contained on a Web page, called from an external file, or even both. For sites with many style declarations, the centralized version i.e. external file, offers the most probable efficiency gains in terms of a website’s management. Before CSS, nearly all of the presentational attributes of HTML documentation was contained in the HTML markup. As well as all font colors, the different background styles and element alignments. Sizes and borders had to be clearly described, and often repeated, within the HTML code. CSS allows authors to move much of that information to a separate style, making for considerably simpler HTML markup.