XML is a text-based markup language that is fast becoming the standard for data interchange.
As with HTML, you identify data using tags (identifiers enclosed in angle brackets, like this: <...>). Collectively, the tags are known as "markup".
But unlike HTML, XML tags identify the data, rather than specifying how to display it. Where an HTML tag says something like "display this data in bold font" ( <b>...</b> ), an XML tag acts like a field name in your program. It puts a label on a piece of data that identifies it (for example: <message>...</message> ).