Acronym for Cascading Style Sheet, It is a World Wide Web Consortium (W3C) standard for style sheets capable of indicating presentation formats (such as fonts, font sizes, and paragraph alignment) for HTML elements. Using syntax, Web authors can incorporate style statements using HTML 4.0’s style attribute, a separate style area (using the STYLE element) within the document’s HEAD element, or a completely different text file (with the .css extension).
The term “cascading” is meant to suggest the various levels of authority; style definitions within the HEAD override external style sheets, while style statements placed within an HTML element override all other style definitions is currently in its Level 2 specification See DeCSS, DVD Regia locking.