"A standard that can be used to pass
data between different programs."

Yup but that is only a small part of the impact that XML is having.

XML is a standard and in technological terms it is not perfect, but, it is what this standard
allows and is achieving that make it one of the biggest impacts to hit IT in its history.

Firstly - the world has gone OOT for application development - objects & message passing
between them - XML allows data objects to be deserialized (flattened out) and passed
between otherwise incompatible objects, languages and technologies, historically this
allows us to move on from passing data between incompatible systems & software by
way of data manipulation middleware be it from back in the days of modularized &
structured programs thru to todays OOT languages and OSes & application products.
In OOT we had the usual hostile camps creating incompatible means of communicating
between objects - COM+, CORBA, RMI etc: and then there was the burgeoning middleware
mess that attempted to glue these incompatible object technologies together with messy
things like IDL and Object Request Brokers - plus the messages passed were usually in
binary & meaningless to humans wanting to observe the data flow.

XML is a meta-language - i.e. it can be redefined for as many different uses as users want
- the DTD or Schema defines a particular data format and these schemas are devised in a
way that allows them to be accessible universally so that any party who wants to work with
a particular data definition can do so.

But one of the greatest things of all about XML is that almost everybody from IT competitors
thru to industry groups and standards bodies, are endorsing XML and XML sub-languages.
The concept is so simple but so amazingly powerful that it can be said that XML paved the way
forward for the whole IT industry and the world of electronic business where passing messages
(data) is what drives business.

Web Services is one concept that can be built on XML - in a sense it can be called
an XML based technology.

Also unlike previous IT advances, XML does not require businesses to throw out their existing
systems or investments - XML will allow add-on wrappering of existing data such that current
investments are protected.

XML is the basis for the 'new wave' of middleware and it is compatible no matter
what language or OS or server or application. Providing the schema is common
each system should be able to recognise the message - and humans can read the data in a
more meaningful way than was possible with COM+, Corba/IIOP & RMI messages.

The impact on IT is somewhat equivalent to when world trade changed for ever once
everyone adopted Container standards for shipping goods.

It changed the designs of Aircraft, trains trucks roads ports etc: etc: etc: & world trade
boomed.

Cheers

Doug