What do you understand by CSS? Write the advantages of CSS?

Cascading Style Sheets, fondly referred to as CSS, is a simple design language intended to simplify the process of making web pages presentable. Cascading Style Sheets (CSS) is a style sheet language used to describe the presentation semantics (that is, the look and formatting) of a document written in a markup language. Its most common application is to style web pages written in HTML and XHTML, but the language can be applied to any kind of XML document, including SVG and XUL.

Advantages of CSS:

Flexibility-By combining CSS with the functionality of a Content Management System, a considerable amount of flexibility can be programmed into content submission forms. This allows a contributor, who may not be familiar or able to understand or edit CSS or HTML code to select the layout of an article or other page they are submitting on-the-fly, in the same form.

Page reformatting-With a simple change of one line, a different style sheet can be used for the same page. This has advantages for accessibility, as well as providing the ability to tailor a page or site to different target devices. Furthermore, devices not able to understand the styling will still display the content

CSS saves time –We can write CSS once and then reuse same sheet in multiple HTML pages. We can define a style for each HTML element and apply it to as many Web pages as we want. All styling is kept in a limited number of style sheets. The positive impact this has onsite maintenance can’t be overestimated—editing one style sheet is obviously more efficient than editing 10,000 HTML files!

Pages load faster –If we are using CSS, We do not need to write HTML tag attributes every time. Just write one CSS rule of a tag and apply to all the occurrences of that tag. So less code means faster download times. The overall saving in bandwidth is measurable. Since the style sheet is cached after the first request and can be reused for every page on the site, it doesn’t have to be downloaded with each web page. Removing all presentational markups from your web pages in favor of using CSS also reduces their size and bandwidth usage—by more than 50% in many documented cases. This benefits the site owner, through lower bandwidth and storage costs, as well as the site’s visitors, for whom the web pages load faster.

Easy maintenance –To make a global change, simply change the style, and all elements in all the web pages will be updated automatically. The positive impact this has onsite maintenance can’t be overestimated—editing one style sheet is obviously more efficient than editing 10,000 HTML files!

Superior styles to HTML –CSS has a much wider array of attributes than HTML so we can give far better look to our HTML page in comparison of HTML attributes. The separation of content from presentation makes it easier for site owners to reuse the content for other purposes, such as RSS feeds or text-to-speech conversion.

Multiple Device Compatibility –Style sheets allow content to be optimized for more than one type of device. By using the same HTML document, different versions of a website can be presented for handheld devices such as PDAs and cell phones or for printing. Separate styling rules can be used for different output media.

Global web standards –Now HTML attributes are being deprecated and it is being recommended to use CSS. So it’s a good idea to start using CSS in all the HTML pages to make them compatible to future browsers.