CSS – „Cascading Style Sheet” are used to format the layout of Web pages. They can define text styles, table sizes, and other aspects of Web pages that previously could only be defined in a page’s HTML. CSS helps Web developers create a uniform look across several pages of a Web site. Instead of defining the style of each table and each block of text within a page’s HTML, commonly used styles need to be defined only once in a CSS document. Once the style is defined in cascading style sheet, it can be used by any page that references the CSS file.