Cascading Style Sheet is the expansion of CSS. It is a style-sheet language which is used to describe how the webpage is to be presented. Commonly CSS is used to give styles to the webpages written in HTML and XHTML. But it can also be applied to XML including SVG and XUL. The external styles are stored in the CSS files and can save lots of work and time because the developers can control the style and layout of the webpage all at once. CSS is mainly designed to enable the separation of the webpage content from the webpage presentation including colors, fonts and layouts. The CSS sheet can be shared with multiple webpages. It provides more flexibility and reduces more complexity.
For the CSS to work properly, the mark-up in the webpage must be free of errors. The style sheet can be applied to a webpage internally or externally. The style sheet consists of a list of rules. All the webpage presentations are included in the HTML mark-up but the styles such as background styles, font colors, data alignments, borders and size which are often repeated can be solved by giving the style coding in the style sheet at one time. This saves the time as well as makes the HTML document a simple one. Retyping the same tag again and again in the same webpage leads to a big HTML file. The CSS style sheet act as a partner to the HTML code and takes care of the layout fonts, colors, the overall appearance of the site.