What is XML?

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.

If you save XML file in your computer, it would have an XML extension (f.e. products.xml).

You can use an XML type data feed to import your products into WiseXML.
WiseXML can also export your products in XML format for various integrations.