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.

XML Structure
XML Declaration
XML documents may begin by declaring some information about themselves, as in the following example:
<?xml version="1.0" encoding="UTF-8" ?> 
A markup construct that begins with < and ends with >. Tags come in three flavors: 
start-tags; for example: <section>
end-tags; for example: </section>

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