How do you open xml files?

XML can be opened with nearly any text editors, XML is an open standard language and anybody can define their own XML document.

Example:
The example below can be anything I will just demonstrate with the theme of a bookstore. Just say you need to store information about books and display them in a web page.

<?xml version="1.0"?>
<bookstore> (This is the bookstore tag)
<history> (If you wanted to catergorize your books, I choose a history tag)

<book name="Classical Rome" isbn="236217836"> (This is an example book)
<author>Pontius Suitonius</author>
<date>12.12.12</date>
</book>

<book name "Ancient Britain" isbn="4357346538">(Here is another example book)
<author>Simon Etherington</author>
<date>12.12.12</date>
</book>

</history> (The History tag closes)
</bookstore> (The bookstore tag closes)

NB! Comments are not used in XML, the example above uses (asdsadsa) for illustration.