HTML (the Hypertext Markup Language) and CSS (Cascading Style Sheets) are two of the core technologies for building Web pages. HTML provides the structure of the page, CSS the (visual and aural) layout, for a variety of devices.
link:http://www.w3.org/standards/webdesign/htmlcss
HTML is the language for describing the structure of Web pages.
With HTML, authors describe the structure of pages using markup.
CSS is the language for describing the presentation of Web pages, including colors, layout, and fonts.
1.markup the structure, using markup