CSS (Cascading Style Sheet)
CSS is used by both the authors and readers of web pages to define colours, fonts, layout and other aspects of document presentation. It is designed primarily to enable the separation of document structure (written in HTML or a similar markup language) from document presentation (written in CSS). This allows improved content accessibility, greater flexibility and control of presentational characteristics.
HTML (Hyper Text Markup Language)
A cross-platform text-formatting system for creating web pages, including copy, images, sounds, frames, animation and more.