Cascading Style Sheets is a style sheet language used to add fonts, spacing and coloring (‘styles’) to Web documents. CSS thus decides the ‘look’ of the website and makes it presentable. It is also used to enhance the usability and appeal of the website. CSS is independent of HTML, and can actually simplify a site’s HTML files, enabling an increase in search engine rankings (thus making your site more popular). CSS allows you to change the style of the web page by changing just one file (without needing to make any changes to the content of the page).