A CSS or cascading style sheet is used to style web pages. It offers designers greater control over both the overall look and feel of the design as well as over the presentation of content and function.
Cascading style sheets are helpful in search engine optimization because they allow you to present content in a way that is both search engine-friendly and user-friendly.
Search engines consider content that appears closest to the top of the page to be most important. Actually, a search engine “reads” your content in much the same way as your English teacher. To simplify: the opening content tells what the page is about; the middle content supports the opening content; and the closing content restates the opening content. When the keywords are used effectively throughout, the search engine determines what your web page is about. The more focused your content and the clearer your presentation the better the search engine will be at classifying it. CSS allows you to present your highly focused web content at the top of the HTML page instead of forcing it to appear below a huge string of programming code. This way the search engines see your page content first – the same content intended for the end-user – making it easier for them to index it.
CSS offers many ways to control the presentation of web content so that it is not diluted with items that do not clarify to the search engines exactly what the page is about.