CSS
HTML is the Structure or core of the page - it lets you format text, add images, create links, etc. It enables you to save as a text file that any BROWSER can read
CSS (Cascading Style Sheets) controls the Presentation or appearance of the page/pages. It is a collection of appearances or styles that control the visual aspects of the content - color, font, layout, etc. If you need to make changes they will cascade throughout the site. CSS enables you to separate the content from the design.
CSS Syntax (CSS WC3 tutorial)

3 types of Selector
- Element selector
- ID selector #yourname
- Class selector .yourname / pseudo-Class Selector
HOW TO:
Inline
<p style="color: blue; margin: center;">Text here</p>
Internal Style Sheet
located in the head of the document using the <style> tag
External Style Sheet
insert a link to the css document into the head of the page and styles are saved in a text file with the .css extension.
<head>
<link rel="stylesheet" type="text/css" href="mystyle.css">
</head>s
CSS BOX MODEL