CSS is also known as Cascading Style Sheets, it is how you define your website through italics, setting your typeface, creating colors and so much more. The css is to set-up the formatting and positioning of each element of the site. Css is the better part of HTML because it is where you get to creatively design the site.
Writing XHTML
XHTML stands for Extensible HyperText Markup Language and CSS is the mechanism for styling XHTML.In XHTML the content is already designed for you, meaning the tag is already set for you because the tag already has the content it contains. Along with the tags there is also A DTD which is known as a document type definition. This helps the XHTML know the tags content.
Knowing Attributes
An attribute is created by a name and a value and separted by an = sign. Attriubutes are used to expand on information about what an element is and does. A few things to remember when using attributes is the do them in lowercase, use double quotes, and use them for specific elememts. Here is an example of what it looks like name="value"