From http://www.w3schools.com (Copyright Refsnes Data)

WSDL and UDDI

Universal Description, Discovery and Integration (UDDI) is a directory service where businesses can register and search for Web services.

What is UDDI

UDDI is a platform-independent framework for describing services, discovering businesses, and integrating business services by using the Internet.

UDDI stands for Universal Description, Discovery and Integration
UDDI is a directory for storing information about web services
UDDI is a directory of web service interfaces described by WSDL
UDDI communicates via SOAP
UDDI is built into the Microsoft .NET platform

What is UDDI Based On?

UDDI uses World Wide Web Consortium (W3C) and Internet Engineering Task Force (IETF) Internet standards such as XML, HTTP, and DNS protocols.

UDDI uses WSDL to describe interfaces to web services

Additionally, cross platform programming features are addressed by adopting SOAP, known as XML Protocol messaging specifications found at the W3C Web site.

UDDI Benefits

Any industry or businesses of all sizes can benefit from UDDI

Before UDDI, there was no Internet standard for businesses to reach their customers and partners with information about their products and services. Nor was there a method of how to integrate into each other's systems and processes.

Problems the UDDI specification can help to solve:

Making it possible to discover the right business from the millions currently online
Defining how to enable commerce once the preferred business is discovered
Reaching new customers and increasing access to current customers
Expanding offerings and extending market reach
Solving customer-driven need to remove barriers to allow for rapid participation in the global Internet economy
Describing services and business processes programmatically in a single, open, and secure environment

How can UDDI be Used

If the industry published an UDDI standard for flight rate checking and reservation, airlines could register their services into an UDDI directory. Travel agencies could then search the UDDI directory to find the airline's reservation interface. When the interface is found, the travel agency can communicate with the service immediately because it uses a well-defined reservation interface.

Who is Supporting UDDI?

UDDI is a cross-industry effort driven by all major platform and software providers like Dell, Fujitsu, HP, Hitachi, IBM, Intel, Microsoft, Oracle, SAP, and Sun, as well as a large community of marketplace operators, and e-business leaders.

Over 220 companies are members of the UDDI community.