CSS3: CSS3 stands for Cascading Style Sheet level 3, which is the advanced version of CSS. It is used for structuring, styling, and formatting web pages. Several new features have been added to CSS3 and it is supported by all modern web browsers.CSS3 is the 3rd level and latest version of CSS, the stylesheet language of web used to control the styling of a website. CSS3 or CSS Level 3 is the latest version of css. CSS3 includes CSS 1, CSS 2, CSS 2.1 ( previous version of css) and CSS3 specifications. CSS3 is the third level of CSS specifications.