CSS is the language for describing the presentation of Web pages. This includes colors, layout, and font information, as well as how to change the presentation on different types of devices, such as those with large screens, small screens, or printers. CSS is independent of HTML and can be used with any XML-based markup language. The separation of HTML from CSS makes it easier to maintain the code, share style sheets across pages, and tailor pages to different environments. This is referred to as the separation of structure (or content) from presentation.
In the beginning, the Web was simple. It consisted of plain, unadorned text. Headings were in large, bold type; links were blue and underlined—and that was it. The lack of images and any attempt at styling the page seem odd to us now, but the Web’s origins lie in the scientific community, not with artists or graphic designers. However, it didn’t take long before people other than scientists realized the potential of the Web and began to demand the ability to include images.
Once images began to brighten up web pages, designers wanted not only a way to make text look more interesting but also to lay out the contents of a page in more attractive ways than just headings and paragraphs. The original specification was published by the World Wide Web Consortium (W3C) at the end of 1996. We have CSS to thank for faster and more beautiful looking web pages.