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XML
What is an XML file?
The verbose ancestor of JSON. Still the backbone of enterprise and government data exchange.
What XML is
XML is a plain-text format you can open in any editor. It is used for moving data between programs.
The extension is .xml, and the full name is Extensible Markup Language. Both matter less than what the file can hold, which is what the rest of this page is about.
Where XML came from
W3C published it in 1998. The specification is XML 1.0.
A format that has been readable for that long is a format worth trusting with something you want back in ten years.
The specification is public
Anyone can implement it without asking permission or paying a licence, which is why it turns up in so many programs and why files written twenty years ago still open.
Nothing is thrown away
XML stores its content exactly. Saving it again changes nothing, so it can be opened, edited and re-saved as often as you like without accumulating damage — which is what makes it a working format rather than a delivery one.
You can leave notes in it
XML has a comment syntax, which is the difference between a file a person maintains and one a program writes. Comments are the first thing lost converting to a format without them, and nothing warns you.
What opens XML
Visual Studio Code and oXygen XML Editor read it, and so do most programs of the same kind.
If a file will not open, the format is rarely the problem — it is more often that the program predates it. Converting to something older is the reliable way past that, and it is what the rest of this site is for.
Opening it in a browser
Every current browser reads it.
That makes it a safe thing to put on a page or attach to a message without wondering what the other end has installed.
It is a working format
XML is meant to be opened and changed. Keep the file in this format for as long as the work is going on, and export from it whenever a finished copy is needed.
The facts, in one place
| Extension | .xml |
|---|---|
| Media type | application/xml, text/xml |
| Published by | W3C |
| First published | 1998 |
| Specification | XML 1.0 |