A term that many are using but few are providing usable definitions for.

Adam Bosworth of BEA recently stepped up to the plate and offered this definition:

The term Web Services refers to an architecture that allows applications to talk to each other. Period. End of statement.

This definition is authoritative and useful but it also encompasses the entire Internet, TCP/IP, Netware, RPC, SNMP, and USB to name just a few.

The W3C says a web service is:

a software application identified by a URI, whose interfaces and bindings are capable of being defined, described, and discovered as XML artifacts. A Web service supports direct interactions with other software agents using XML-based messages exchanged via Internet-based protocols.