Extensible Markup Language (XML) is a markup language that defines a set of rules for encoding documents in a format that is both human-readable and machine-readable.
In XML every element is described by tags, which are denoted by <…> brackets. Tags always have some name and may optionally contain some attributes and content. Attributes are always put together with the tag name inside the <…> brackets, i.e. <tag attr1="value1" attr2="value2">. On the other hand, the tag content is always put after the brackets and must end with the </tag> element. Inside the tag content you may put text or some other tags, depending on the kind of input you want (and more importantly may) to enter. If a tag does not have any content, this must be indicated by putting the / character before the closing bracket (i.e. <tag/>). Tag attributes are still allowed in such a case.