XML (eXtensible Markup Language) is a standard which allows information to be presented as a structured document. Structured document contains the information organized in a manner where individual data segments are easily machine-readable and interpretable. In the XML document the structure of the data is organized using so-called XML tags. Each individual data segment is marked by start and end tags, where the actual data is shown between these tags. The name of the tag identifies the information within. Tags can be nested:
<Person> <FirstName>James</FirstName> <LastName>Bond</LastName> </Person>
Message schema defines the allowed data structure for certain XML documents, in other words, the sequence, occurrence and structure of tags used for presenting information.
XML's common application areas are electronic data interchange (EDI), data storage and multi-channel publishing.
XML documents can be modified using a standard text editor, but usually you need a specific XML tool.