Cascading Style Sheets or CSS find use for stylizing the web pages and describing the look and formatting of the documents with the help of presentation semantics. This is a style sheet language and finds common application in web pages written in popular markup languages such as HTML and XHTML. However, they have also found use in various types of XML documents such as plain XML, XUL, and SVG among others. The primary aim of using CSS is to separate the document presentation, which includes various elements such as, colors, fonts and layouts from the document content. The document content is the part of the web pages written in the markup languages such as HTML or XHTML. This separation helps in reducing the complexity of the structural content by avoiding the repetition of various such contents, which becomes possible by enabling a number of processes such as allowing tableless website design. The use of CSS also helps in increasing flexibility and control of the various presentation characteristics and resulting in improved content accessibility. Another advantage of using CSS is to enable multiple pages the access to sharing formatting making website design seamless.

The cascade feature of the CSS allows it to formulate priority schemes, which determines the style it would follow if more than one style rule exists. The cascade calculates and assigns priorities or weights to various such design rules, and the results become predictable based on the rule assigned with the highest priority prevailing over others. CSS allows various web pages containing content written in markup languages to have different presentation depending on the nature of the rendering device. Therefore, the same content may vary depending on the rendering device with different styles for screens, print version, Braille based devices or any other forms. Another major advantage of using CSS is that it provides the reader of any document to select the CSS style sheet they prefer. The author of any document may link it to a particular CSS style sheet but the readers can change the style sheet and use one they prefer or might be having on their computer. The ability to overwrite the specifications that the author has set comes as an added flexibility in website design.

CSS allows its users to download it just once and then use it on multiple web pages on their website. The removal of all the layout and styles from the HTML renders them much smaller which is an extremely useful feature of CSS. Since CSS requires its users to download it only once, it frees up considerable space on the bandwidth and enables users to have more visitors on their websites. This makes it much more profitable for website owners thriving on online traffic. Another major advantage of using CSS instead of table based page design is that the search engines show the content of web page using it in their results. The search engines consider the start of the HTML code to be the essential content, and CSS allows its users to move the page description to the start of the HTML code. These are some of the major advantages of using Cascading Style Sheets for stylizing and formatting when it comes to website design.