When is it OK to use an XML file to save information?

Question

What reason could there be for using an XML to save information?

Answer 1

It's a portable, parsable standard.

So if you have data that needs to be read by several different programs (and possibly people) you could use XML.

It is also relatively easy to validate and transform (via XSLT) into other formats.

Obviously you could use other formats, but that doesn't stop you using XML.