CSS or Cascading Style Sheets is a type of style sheet language used when creating a website. While HTML describes the structure of a webpage, CSS describes the layout and styling. CSS allows you to display specific designs, layouts, and other style variations on multiple pages at once. You can define page fonts, font color, title page design, table design, and many other things using CSS. Cascading Style Sheets is a relatively new introduction to web development, although it is just as simple to learn as HTML is.