The Cascading Style Sheets, commonly known as CSS, is a style sheet language used to describe the presentation semantics of a document written in a markup language, specially webpages written in XHTML and HTML though it can be applied to any XML file. More easily explained, it is simply used for adding style to documents. HTML did not intend to contain tags for formatting a document, but to define the content of a document. When tags were added it started a problem for web developers. Development of large web sites became a long and expensive process. CSS was created to solve this problem. Finally In HTML 4.0, all formatting could be stored in a separate CSS file, and all browsers support CSS nowadays. Among the advantages, we can find the flexibility of the programming, the separation of content from presentation, the site-wide consistency, the open bandwidth which increases speed and the easy page reformatting. Reources: http://en.wikipedia.org/wiki/Cascading_Style_Sheets http://www.w3.org/Style/CSS/ http://www.w3schools.com/css/ http://www.csszengarden.com/
