What is CSS?

CSS or Cascading Style Sheets are formatting and design instructions that go hand in hand with HTML. CSS provides a way of extending the formatting instructions provided by HTML tags so that a web page's layout, colours and fonts can be manipulated.

CSS in the same way as HTML is read and understood by your web browser. An HTML web page references design and formatting instructions within a CSS file, these instructions are then interpreted by your web browser and the colours, fonts and layout you see are all governed by the CSS.