XHTML code has only minor differences from HTML. For using XHTML, you must follow the following rules:
• Must use an XHTML document type at the top of the file
• All tags must be in lowercase
• All tags must have a close tag
• All attributes must have quotes
• If tags do not have a close tag, such as a <br> or <img> tag, they must be written as self ending: <br /> or <img src=”image.jpg” />