At first glance, XMLports are for importing and exporting data, similar to the Dataports. But XMLports differ considerably in their operation, setup, and intended usage. XMLport objects can only be used for XML-formatted data. They must be "fired off" by some other routine (i.e. cannot be run directly through a menu entry). XML stands for eXtensible Markup Language. XML is a markup language much like HTML. XML was designed to describe data so that it would be easier to exchange data between dissimilar systems, for example, between your NAV ERP system and your accounting firm's financial analysis and tax preparation system.
XML is designed to be extensible, which means that you can create or extend the definition so long as you communicate the revised XML format to your correspondents. There is a standard set of syntax rules to which XML formats must conform. XML is becoming more and more important because most software uses XML. For example, the new versions of Microsoft Office are quite XML "friendly".