XHTML mark up: a set of elements with attributes. Element is an open tag, some content then a close tag. If no content, element defined by empty tag.

• An open tag consists of:
  • Left angle bracket (<) followed immediately by the tag name
  • May have one or more attributes (id="3") separated by spaces
  • Right angle bracket (>) possibly with spaces before
• A close tag consists of:
  • Left angle bracket (<) followed immediately by a slash (/) and the tag name
  • Right angle bracket (>) possibly with spaces before
• An empty tag represents both the open and close tag:
  • Left angle bracket (<) followed by the tag name possibly with spaces after
  • A slash (/) followed by a right angle bracket (>)
• Attributes qualifies the meaning of an element
  • Appear within the opening tag separated by spaces
  • Attribute name followed by = followed by text string in quotes (either " or ')
  • Cannot mix the quotes (abc="xyz' is not valid)
  • Same attribute name cannot appear twice

<title>Title of your document</title>
<hr />
<p class="note">and an <em>enclosed</em> element</p>