1. Elements that are contained within the root element,represented by an opening and closing tag,Data and other elements reside between them.
2. XML allows you to use empty elements. An empty element is one without a closing tag. Like HTML you must close empty elements with a forward slash before the > symbol. For example, <br />.
3. Elements can also contain one or more attributes. An attribute is a name/value pair, that you place within an opening tag, which allows you to provide extra information about an element.