Let us suppose a scenario where your website, having 10 html pages, requires the modification in the way the text looks...color, font or size. If you are using the simple html coding then you are required to open all the pages individually and modify the text on each page. While you are doing this you might be thinking that instead of editing each page individually...if you were able to modify the font at one place to reflect the changes in all the 10 pages. That's where CSS comes into picture.