What is CSS? Today we will learn what is CSS? How to learn? What is the full form of CSS? Types of CSS and How to Use CSS in Web Development?. As we know that Cascading Style Sheets (CSS) are used for web designing. CSS was developed in 1996 by the W3C(World Wide Web Consortium). It is a style sheet language, which is used to create beautiful and attractive documents written in a markup language, including elements such as Layout, Colors and Fonts.