The element in an Extensible Markup Language (XML) document that contains all other elements in that document. It is the top-level element of an XML document and must be the first element in the document.
Each XML document has one, and exactly one single root element. This element encloses all following elements and is therefore the parent element to all the other elements. The end-tag of the child element is always before the end-tag of the parent element - this is called nested elements.