It’s an XML. Since the letter X begins with a vowel sound, we use the article "an".

It’s an XML. Since the letter X begins with a vowel sound, we use the indefinite article "an" before the abbreviation XML (eXtensible Markup Language).

An XML element can be used to store text elements and attributes.

A XML element can be used to store text elements and attributes.

Be aware that the rule for using "a" or "an" is based on the initial sound of the following word, not how it's spelled.

You can create an XML document by using a text editor.

And we say "an X" (not "a X").

An XML file is typically used to structure data.

Follow the same practice with other abbreviations that begin with the letter "X" and are pronounced as separate letters; for example, we say an X-ray or an XL (eXtra Large).